全文获取类型
收费全文 | 9435篇 |
免费 | 832篇 |
国内免费 | 138篇 |
专业分类
耳鼻咽喉 | 72篇 |
儿科学 | 350篇 |
妇产科学 | 283篇 |
基础医学 | 1155篇 |
口腔科学 | 394篇 |
临床医学 | 974篇 |
内科学 | 1846篇 |
皮肤病学 | 182篇 |
神经病学 | 1038篇 |
特种医学 | 540篇 |
外科学 | 1235篇 |
综合类 | 200篇 |
一般理论 | 9篇 |
预防医学 | 923篇 |
眼科学 | 170篇 |
药学 | 629篇 |
中国医学 | 8篇 |
肿瘤学 | 397篇 |
出版年
2022年 | 78篇 |
2021年 | 155篇 |
2020年 | 117篇 |
2019年 | 139篇 |
2018年 | 139篇 |
2017年 | 131篇 |
2016年 | 138篇 |
2015年 | 148篇 |
2014年 | 227篇 |
2013年 | 325篇 |
2012年 | 372篇 |
2011年 | 404篇 |
2010年 | 244篇 |
2009年 | 285篇 |
2008年 | 378篇 |
2007年 | 492篇 |
2006年 | 391篇 |
2005年 | 420篇 |
2004年 | 374篇 |
2003年 | 364篇 |
2002年 | 345篇 |
2001年 | 290篇 |
2000年 | 295篇 |
1999年 | 288篇 |
1998年 | 141篇 |
1997年 | 140篇 |
1996年 | 131篇 |
1995年 | 140篇 |
1994年 | 110篇 |
1993年 | 112篇 |
1992年 | 214篇 |
1991年 | 183篇 |
1990年 | 183篇 |
1989年 | 157篇 |
1988年 | 158篇 |
1987年 | 151篇 |
1986年 | 170篇 |
1985年 | 150篇 |
1984年 | 132篇 |
1983年 | 106篇 |
1982年 | 80篇 |
1981年 | 65篇 |
1980年 | 65篇 |
1979年 | 101篇 |
1978年 | 76篇 |
1975年 | 72篇 |
1974年 | 76篇 |
1973年 | 65篇 |
1972年 | 67篇 |
1968年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
91.
Repeat sequences in block 2 of Plasmodium falciparum merozoite surface protein 1 are targets of antibodies associated with protection from malaria
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Polley SD Tetteh KK Cavanagh DR Pearce RJ Lloyd JM Bojang KA Okenu DM Greenwood BM McBride JS Conway DJ 《Infection and immunity》2003,71(4):1833-1842
Human antibodies to the block 2 region of Plasmodium falciparum merozoite surface protein 1 (MSP1) are associated with a reduced prospective risk of clinical malaria. Block 2 is highly polymorphic, but all known alleles can be grouped into three major types. Two of these types (the K1-like and MAD20-like types) contain type-specific sequences (found in all alleles of a particular type) that flank polymorphic tripeptide repeats. These repeats contain both type-specific and subtype-specific sequences. To evaluate the antibody recognition of these parts of block 2, a new panel of six recombinant proteins was used (fused type-specific flanking sequences and two representative repeat sequences for each of the K1-like and MAD20-like types separately). Extensive testing of these antigens and full-length block 2 antigens showed that human serum immunoglobulin G antibodies induced by infection can recognize (i) type-specific epitopes in the repeats, (ii) subtype-specific epitopes in the repeats, or (iii) type-specific epitopes in flanking sequences. A large prospective study in The Gambia showed that antibodies to the repeats are strongly associated with protection from clinical malaria. The results are important for design of a vaccine to induce protective antibodies, and they address hypotheses about repeat sequences in malaria antigens. 相似文献
92.
Katz JL Spencer P Nomura T Wagh A Wang Y 《Journal of biomedical materials research. Part A》2003,66(1):120-128
In a previous study, we reported the upper limit of Young's modulus of the unprotected protein at the dentin/adhesive interface to be 2 GPa. In this study, to obtain a more exact value of the moduli of the components at the d/a interface, we used demineralized dentin collagen with and without adhesive infiltration. The prepared samples were analyzed using micro-Raman spectroscopy (micro RS) and scanning acoustic microscopy (SAM). Using an Olympus UH3 SAM (Olympus Co., Tokyo), measurements were recorded with a 400 MHz burst mode lens (120 degrees aperture angle; nominal lateral resolution, 2.5 microm). A series of calibration curves were prepared using the relationship between the ultrasonically measured elastic moduli of a set of known materials and their SAM response. Finally, both the bulk and bar wave elastic moduli were computed for a set of 13 materials, including polymers, ceramics, and metals. These provided the rationale for using extensional wave measurements of the elastic moduli as the basis for extrapolation of the 400 MHz SAM data to obtain Young's moduli for the samples: E = 1.76 +/- 0.00 GPa for the collagen alone; E = 1.84 +/- 0.65 GPa for the collagen infiltrated with adhesive; E = 3.4 +/- 1.00 GPa for the adhesive infiltrate. 相似文献
93.
Neutrophil activity in abscess-bearing mice: comparative studies with neutrophils isolated from peripheral blood, elicited peritoneal exudates, and abscesses. 总被引:1,自引:5,他引:1
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P H Hart L K Spencer M F Nulsen P J McDonald J J Finlay-Jones 《Infection and immunity》1986,51(3):936-941
Intraabdominal abscesses were induced in mice by intraperitoneal inoculation of Bacteroides fragilis and Escherichia coli plus bran as the abscess-potentiating agent. Six- or seven-day-old abscesses were mechanically disaggregated in buffer, and the cells obtained were fractionated on discontinuous Percoll density gradients. Neutrophil populations of different density, each approximately 90% pure, were isolated. When the abscess-derived neutrophils were subsequently incubated with normal serum in vitro under aerobic conditions, the viability of the gram-negative bacteria that had been phagocytosed within the abscess did not change significantly. This anergy to intracellular bacteria (on subsequent incubation in vitro under optimal conditions for phagocytic killing) was also found for neutrophils that had been obtained from abscesses induced by a mixture that included Proteus mirabilis plus B. fragilis and from those induced by E. coli plus P. mirabilis. While unable to significantly kill intracellular organisms that had been phagocytosed in vivo, the abscess-derived neutrophils could engulf and kill organisms to which they were exposed in vitro. Neutrophils from abscesses induced by P. mirabilis only plus bran killed that organism introduced in vitro significantly more effectively than the organisms that had been engulfed in vivo. In contrast, neutrophils from abscesses induced by the gram-positive organism Staphylococcus aureus plus bran were able to kill their intracellular organisms on subsequent incubation in vitro as effectively as they could kill added S. aureus. Neutrophils isolated from the peripheral blood and from induced peritoneal exudates of abscess-bearing mice were able to phagocytose and kill organisms in vitro with greater efficiency than abscess-derived neutrophils. The mechanism whereby neutrophils from abscesses induced by the gram-positive organism S. aureus can kill the organisms phagocytosed in vivo on subsequent in vitro incubation, in contrast to the relative anergy to their intracellular organisms displayed by neutrophils derived from abscesses induced by combinations of gram-negative bacteria, is not known. 相似文献
94.
Jacques R. Caldwell David E. Pearce Craig Spencer Rosmarie Leder Robert H. Waldman 《The Journal of allergy and clinical immunology》1973,52(4):225-230
Immunologic studies were performed on 5 patients with pigeon breeders' disease. Intradermal injection of pigeon serum produced an immediate wheal-and-flare reaction within 15 minutes and a secondary Arthus-type reaction within 4 to 8 hours. Immunofluorescent studies of the secondary reaction site showed IgG, C3, and C4 in 2 patients. Patients' sera produced multiple precipitin bands with pigeon serum when reacted by double diffusion in gel. IgG antibody isolated from each of the patients' serum formed precipitating immune complexes that fixed large amounts of complement (C4) when added to fresh human serum. Peripheral blood lymphocytes from 4 of the 5 patients produced macrophage migration inhibitory factor (MIF) when challenged with dilute pigeon serum. These studies are the first to show complement fixing antibodies and macrophage MIF production by lymphocytes from patients with hypersensitivity lung disease and suggest that both humoral and cellular immunity may be important in the pathogenesis of these disorders. 相似文献
95.
Development of neural processes underlying integration of phonological and orthographic information were assessed by measuring event-related brain potentials (ERPs), judgment accuracies and reaction times (RTs) in 20 children (9-10 years) and 20 adults performing visual rhyme judgments. Half the trials were phonologically and orthographically congruent across the prime-target pairs (e.g., thrown-own, cake-own), and half were incongruent (e.g., gown-own, cone-own). For both children and adults, behavioral performance was most affected when different phonological representations had to be encoded from similar orthographic representations (e.g., gown-own), and the amplitudes of the N350 reflected effects of both rhyme and phonological/orthographic congruency. Latencies of the N350 were shorter over the left hemisphere only in adults, and phonological/orthographic incongruence produced greater delays in children's processing. Therefore, it appears that neural systems mediating rhyming judgments develop early; however, adults exhibit increased efficiency for left-hemisphere processing and are less affected by interference from incongruent phonological and orthographic codes. 相似文献
96.
Audit and academic departments of general practice: a survey in the United Kingdom and Eire.
下载免费PDF全文
![点击此处可从《The British journal of general practice》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J A Spencer 《The British journal of general practice》1992,42(361):333-335
A questionnaire and telephone survey was carried out in April 1991 of all 31 academic departments of general practice in the United Kingdom and Eire; 30 departments responded. The aim of the study was to assess the departments' level of involvement in teaching about audit in the undergraduate curriculum, their role in the development of audit in primary care including involvement with medical audit advisory groups, whether they undertook teaching about audit to other health professionals and whether they were involved in audit related research. Eleven of 27 responding undergraduate departments provided formal teaching about audit and five intended to introduce it in the near future. Respondents expressed concerns about teaching audit to undergraduates, including lack of time in the curriculum, difficulties making the teaching relevant and interesting, and a lack of expertise and knowledge of the subject among the staff. All 29 departments in the UK were represented on medical audit advisory groups, and audit related research was being carried out in 24 undergraduate departments. The role of academic departments of general practice in the development of audit in primary care is discussed. 相似文献
97.
98.
99.
Bradley Q. Fox Peninah F. Benjamin Ammara Aqeel Emily Fitts Spencer Flynn Brian Levine Elizaveta Maslak Rebecca L. Milner Benjamin Ose Michael Poeschla Meghna Ray Maeve Serino Sahaj S. Shah Kelly L. Close 《Clinical Diabetes》2021,39(2):160
To the best of our knowledge, there are no published data on the historical and recent use of CGM in clinical trials of pharmacological agents used in the treatment of diabetes. We analyzed 2,032 clinical trials of 40 antihyperglycemic therapies currently on the market with a study start date between 1 January 2000 and 31 December 2019. According to ClinicalTrials.gov, 119 (5.9%) of these trials used CGM. CGM usage in clinical trials has increased over time, rising from <5% before 2005 to 12.5% in 2019. However, it is still low given its inclusion in the American Diabetes Association’s latest guidelines and known limitations of A1C for assessing ongoing diabetes care.The availability of reliable continuous glucose monitoring (CGM) systems has proven to be a major innovation in diabetes management and research. Most current CGM systems are approved for 7- to 14-day use and use a wire-tipped glucose oxidase sensor inserted in subcutaneous tissue to monitor glucose concentrations in interstitial fluid. One implanted CGM system is approved for longer-term use (90–180 days); it operates with fluorescence-based technology. CGM sensors record a glucose data point every 1–15 minutes (depending on the system), collecting far more granular data and information on glycemic patterns than self-monitoring of blood glucose (SMBG) alone. Real-time CGM or intermittently scanned CGM systems send data continuously or intermittently to dedicated receivers or smartphones, whereas professional CGM systems provide retrospective data, either blinded or unblinded, for analysis and can be used to identify patterns of hypo- and hyperglycemia. Professional CGM can be helpful to evaluate patients when other CGM systems are not available to the patient or the patient prefers a blinded analysis or a shorter experience with unblinded data.In the 20 years since CGM systems first became available to people with diabetes, technological improvements, particularly pertaining to accuracy and form factor, have made CGM increasingly viable for both patient use and clinical investigation (1,2). Average sensor MARD (mean absolute relative difference; a summary accuracy statistic) has decreased from >20 to <10% (3–10), including two systems that do not require fingerstick calibrations and three that are approved to be used for insulin dosing (11). Concurrently, size, weight, and cost of CGM systems have all decreased, while user-friendliness and convenience have increased (12).To encourage use of CGM-derived data, researchers and clinicians have worked to develop a standard set of glycemic metrics beyond A1C. In 2017, two international groups of leading diabetes clinical and research organizations published consensus definitions for key metrics, including clinically relevant glycemic cut points for hypoglycemia (<70 and <54 mg/dL), hyperglycemia (>180 and >250 mg/dL), and time in range (TIR; 70–180 mg/dL) (13,14).CGM-derived metrics provide far greater precision and granularity than is possible with SMBG or A1C data alone (Table 1), enabling clinicians and investigators to better represent inter- and intraday glycemic differences with metrics such as TIR, glycemic variability, and time in hypoglycemia and hyperglycemia (15). Crucially, CGM also allows for the accurate measurement and detection of nocturnal glycemia (16). The use of these metrics enables a more comprehensive understanding of glycemic management that can facilitate individualized treatment for people with diabetes or prediabetes. Although A1C is a useful estimate of mean glucose over the previous 2–3 months, especially when evaluating population health, it is important to include other glycemic outcomes in clinical trials. Furthermore, there is emerging evidence suggesting that TIR predicts the development of microvascular complications at least as well as A1C (17,18).TABLE 1Benefits of CGM Compared With A1C Alone in Assessing Glycemia
Open in a separate windowDespite recent standardization of metrics and an emerging consensus around the importance of including CGM-derived outcomes in clinical trials, to our knowledge, there has been no attempt to estimate the historical and current use of CGM in clinical trials of pharmacological agents for diabetes. We sought to analyze the use of CGM in trials of currently available pharmaceutical agents for the treatment of diabetes. 相似文献
CGM | A1C Alone |
---|---|
Facilitates real-time readings of blood glucose levels | Requires SMBG |
Provides information on glucose variability, including duration of hypo- and hyperglycemia and nocturnal glycemia | Does not provide information on acute glycemic excursions and time in biochemical hypoglycemia and hyperglycemia |
Correlates strongly with 3 months of mean glucose, TIR, and hyperglycemia metrics | Measures average glucose during the past 2–3 months |
Provides information on direction of and rate of change in glucose levels | Does not provide information on direction of or rate of change in glucose levels |
Provides TIR data (time spent between 70 and 180 mg/dL) | Does not have TIR measurement capability |
100.
Primary and revision total knee arthroplasty have become common orthopaedic procedures. The operating surgeon, at times, may be faced with a difficult surgical case due to soft tissue contractures or bone deformities. A review of multiple surgical techniques using soft tissue releases and osteotomies are presented including their potential complications. Although these techniques are aimed at the atypical operative case, the operating surgeon may utilize them for ‘routine’ exposures as well. Importance is focused on the functional integrity of the knee extensor mechanism. 相似文献