全文获取类型
收费全文 | 5509篇 |
免费 | 451篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 39篇 |
儿科学 | 161篇 |
妇产科学 | 82篇 |
基础医学 | 820篇 |
口腔科学 | 71篇 |
临床医学 | 545篇 |
内科学 | 1362篇 |
皮肤病学 | 120篇 |
神经病学 | 658篇 |
特种医学 | 382篇 |
外国民族医学 | 1篇 |
外科学 | 611篇 |
综合类 | 173篇 |
一般理论 | 1篇 |
预防医学 | 356篇 |
眼科学 | 112篇 |
药学 | 296篇 |
中国医学 | 2篇 |
肿瘤学 | 211篇 |
出版年
2021年 | 55篇 |
2020年 | 42篇 |
2019年 | 68篇 |
2018年 | 76篇 |
2017年 | 56篇 |
2016年 | 60篇 |
2015年 | 71篇 |
2014年 | 107篇 |
2013年 | 148篇 |
2012年 | 243篇 |
2011年 | 266篇 |
2010年 | 159篇 |
2009年 | 127篇 |
2008年 | 229篇 |
2007年 | 238篇 |
2006年 | 209篇 |
2005年 | 245篇 |
2004年 | 193篇 |
2003年 | 194篇 |
2002年 | 180篇 |
2001年 | 189篇 |
2000年 | 200篇 |
1999年 | 167篇 |
1998年 | 92篇 |
1997年 | 76篇 |
1996年 | 66篇 |
1995年 | 58篇 |
1994年 | 58篇 |
1993年 | 48篇 |
1992年 | 144篇 |
1991年 | 132篇 |
1990年 | 155篇 |
1989年 | 132篇 |
1988年 | 114篇 |
1987年 | 111篇 |
1986年 | 112篇 |
1985年 | 94篇 |
1984年 | 88篇 |
1983年 | 67篇 |
1982年 | 56篇 |
1981年 | 55篇 |
1980年 | 45篇 |
1979年 | 78篇 |
1978年 | 60篇 |
1977年 | 47篇 |
1976年 | 42篇 |
1975年 | 44篇 |
1974年 | 35篇 |
1973年 | 52篇 |
1970年 | 39篇 |
排序方式: 共有6003条查询结果,搜索用时 15 毫秒
41.
R A Zager E J Teubner S Adler 《Laboratory investigation; a journal of technical methods and pathology》1987,56(2):180-188
To determine whether tubular reabsorption of low molecular weight proteins (LMWPs) alters ischemic tubular injury, rats were infused with 25 mg of lysozyme (isoelectric point (pI) 11.3), cytochrome C (pI 10.6), ribonuclease (pI 8.7), or myoglobin (pI 7.0), and during this time 25 minutes of bilateral renal artery occlusion (RAO) was induced. RAO control rats received either saline or 25 mg of albumin. Renal injury was assessed 24 hours later by blood urea nitrogen, creatinine, and histology. Lysozyme, ribonuclease, and myoglobin each exacerbated ischemic damage (increased tubular necrosis, cast formation, azotemia), but to comparable degrees (e.g., blood urea nitrogen range 75 +/- 8 to 100 +/- 5 mg/dl versus controls, 29 +/- 2 to 36 +/- 7; p less than 0.01). Rendering lysozyme anionic (pI 4.5) by succinylation did not diminish its acute renal failure-potentiating effect. Cytochrome C which is freely filtered but poorly reabsorbed had a minimal impact on the ischemic process. Infusion of LMWPs did not alter blood pressure, renal blood flow, or induce renal injury in the absence of RAO. During a sublethal ischemic event (10 minutes of RAO) LMWP infusion exacerbated proximal tubular luminal membrane damage before an adverse effect on other critical determinants of cell integrity were apparent (adenine nucleotide pools, oxidant stress). We conclude that endocytic LMWP reabsorption by proximal tubules can exacerbate superimposed ischemic tubular necrosis independent of any direct nephrotoxic protein effect. This action is not influenced by protein isoelectric point and appears to be mediated by a primary intensification of ischemic luminal membrane damage. 相似文献
42.
Tenenbaum A Fisman EZ Pines A Shemesh J Shapira I Adler Y Frenkel Y Boyko V Motro M 《Maturitas》2000,36(1):35-42
OBJECTIVES: mitral annular calcification (MAC) occurs mainly in middle-aged and elderly patients and can lead to serious clinical consequences. Male predominance in the prevalence of coronary disease is well-established. Paradoxically, the prevalence of MAC, which is theoretically based on the same etiological mechanisms as coronary atherosclerosis, seems to be predominant in postmenopausal women. The goal of this work was to investigate gender influences on interrelationship between MAC and coronary calcifications (CC) in the same population of middle-aged and elderly patients with increased cardiovascular risk. METHODS: the study comprised 522 patients (284 men and 238 postmenopausal women, aged 52-80 years, mean 65+/-6), who were recruited to the International Nifedipine GITS Study of Intervention as a Goal in Hypertension Treatment (INSIGHT) study in our region. They underwent both fast spiral computed tomography of the heart and echo-Doppler. MAC was defined as advanced when its thickness was > or =5mm; otherwise it was defined as trivial. RESULTS: there were 37 (16%) women and 25 (9%) men with advanced MAC (AMAC), 97 (41%) women and 118 (42%) men with trivial MAC and 104 (44%) women and 141 (50%) men without MAC. The prevalence of any type of CC was significantly higher among men (P=0. 001). In sharp contrast to the distinct male predominance in coronary disease, AMAC was more prevalent among women. In patients without CC prevalence was 9 and 4%, increasing to 16 and 8% in those with nonsevere CC and to 38 and 14% in patients with severe CC, respectively (P=0.001). Multivariate analysis showed that AMAC can predict the presence of severe CC in women and men, with OR of 4.1 and 2.6 (CI 1.2-14.8 and 1.0-10.6) and coronary disease with OR of 2. 5 and 2.5 (CI 0.6-10.6 and 1.0-6.4), respectively. CONCLUSIONS: AMAC signifies a high probability of coronary atherosclerosis in patients of both genders. The inverted gender predominance in the prevalence of annular calcification and CC could be explained by additional etiological (likely osteoporotic) mechanisms of MAC development among postmenopausal women. 相似文献
43.
Analysis of the RNA species isolated from defective particles of vesicular stomatitis virus. 总被引:3,自引:0,他引:3
Serial high multiplicity passage of a cloned stock of vesicular stomatitis virus was found to generate defective interfering particles containing three size classes of RNA, with sedimentaiton coefficients of 31 S, 23 S and 19 S. The 31 S and 23 S RNA species were found to be complementary to both the 12 to 18 S and 31 S size classes of VSV mRNAs. The 19 S class of RNA was found to be partially base-paired. All three RNA species were found to contain ppAp at their 5' termini. 相似文献
44.
45.
46.
High throughput parallel analysis of hundreds of patient samples for more than 100 mutations in multiple disease genes 总被引:5,自引:0,他引:5
Shuber AP; Michalowsky LA; Nass GS; Skoletsky J; Hire LM; Kotsopoulos SK; Phipps MF; Barberio DM; Klinger KW 《Human molecular genetics》1997,6(3):337-347
As more mutations are identified in genes of known sequence, there is a
crucial need in the areas of medical genetics and genome analysis for
rapid, accurate and cost-effective methods of mutation detection. We have
developed a multiplex allele-specific diagnostic assay (MASDA) for analysis
of large numbers of samples (> 500) simultaneously for a large number of
known mutations (> 100) in a single assay. MASDA utilizes
oligonucleotide hybridization to interrogate DNA sequences. Multiplex DNA
samples are immobilized on a solid support and a single hybridization is
performed with a pool of allele-specific oligonucleotide (ASO) probes. Any
probes complementary to specific mutations present in a given sample are in
effect affinity purified from the pool by the target DNA. Sequence-specific
band patterns (fingerprints), generated by chemical or enzymatic sequencing
of the bound ASO(s), easily identify the specific mutation(s). Using this
design, in a single diagnostic assay, we tested samples for 66 cystic
fibrosis (CF) mutations, 14 beta-thalassemia mutations, two sickle cell
anemia (SCA) mutations, three Tay-Sachs mutations, eight Gaucher mutations,
four mutations in Canavan disease, four mutations in Fanconi anemia, and
five mutations in BRCA1. Each mutation was correctly identified. Finally,
in a blinded study of 106 of these mutations in > 500 patients, all
mutations were properly identified. There were no false positives or false
negatives. The MASDA assay is capable of detecting point mutations as well
as small insertion or deletion mutations. This technology is amenable to
automation and is suitable for immediate utilization for high-throughput
genetic diagnostics in clinical and research laboratories.
相似文献
47.
Phorbol myristate acetate and calcium ionophore A23187-stimulated human T cells do not express high-affinity IL-2 receptors 下载免费PDF全文
Phorbol myristate acetage (PMA) and Ca2+ ionophore A23187 mimic early signal transduction pathways and activate purified human T cells to secrete large quantities of interleukin-2 (IL-2) and to proliferate. Despite producing 50-100-fold more IL-2 than phytohaemagglutinin (PHA)-activated peripheral blood lymphocytes (PBL), PMA/A23187-stimulated human T cells proliferate less than cells activated by PHA. Washing the cells to remove PMA/A23187 was found to increase cellular proliferation two to five-fold. High-affinity IL-2R (HA-IL-2R) were found to be expressed by human T cells that had been washed 24 hr after PMA/A23187 stimulation and recultured without stimulus for an additional 48 hr, but not by T cells constantly exposed to PMA/A23187 for 72 hr. Radioligand binding studies with [125I]IL-2 demonstrated that while the alpha (p55) and beta (p70-75) subunits of HA-IL-2R were both present on the constant PMA/A23187-stimulated T cells, they did not appear to associate to form functional HA-IL-2R. This defect in the expression of bio-active HA-IL-2R on constant PMA/A23187-stimulated human T cells seems to account for their low proliferative response. 相似文献
48.
Laura McGillis Nimish Mittal Daniel Santa Mina Joyce So Medha Soowamber Aliza Weinrib Leslie Soever Dmitry Rozenberg Louis Liu Yvonne Tse Joel Katz George S Charames Kieran Murphy Peter Vadas Maxwell P Slepian Scott Walsh Lindsay Wilson Arnon Adler Alyssa Franzese Laura Hussey Dayna‐Lynn Nevay Juan Guzman Hance Clarke 《American journal of medical genetics. Part A》2020,182(3):484-492
The new 2017 diagnostic criteria for hypermobile Ehlers–Danlos Syndrome (hEDS) provide a framework for diagnosing hEDS but are more stringent than the previous Villefranche criteria. Our clinical experience at the GoodHope EDS clinic was that the 2017 criteria left many highly symptomatic patients without a diagnosis of hEDS. We conducted a retrospective cohort study to confirm our clinic experience and assess the accuracy of the 2017 diagnostic criteria for hEDS in patients who had a previous hEDS diagnosis based on the Villefranche criteria. Our study found that 15% (n = 20 of 131) of patients with a prior diagnosis of hEDS met the 2017 diagnostic criteria, and many of the traits used to distinguish hEDS were not significantly more frequent in patients who met 2017 criteria versus those who did not. In both groups objective systemic manifestations were found less frequently than subjective systemic manifestations. Beighton score (BS) as assessed by primary care practitioner was found to be higher than assessment by EDS practitioner in 81% (n = 74 of 91) of cases. Generalized joint hypermobility was confirmed in only 46% (n = 51 of 111) of patients who had a previous diagnosis of hEDS. Higher BS did not correlate with increased number of systemic manifestations in our cohort. Common comorbidities of hEDS were found with similar frequency in those who met 2017 criteria and those who did not. Based on our cohort, the 2017 hEDS diagnostic criteria require refinement to improve its diagnostic accuracy. 相似文献
49.
M. Willems L. Sheng T. Roskams B. Ramdani J. M. Doutrelepont F. Nevens P. Durez S. Treille M. Adler V. Desmet J. Fevery S. H. Yap 《Journal of medical virology》1994,44(3):266-271
Recently, evidence has been presented for a possible association between hepatitis C virus (HCV) infection and essential mixed cryoglobulinemia (EMC). Eleven consecutive patients with EMC and two with cryoglobulinemia type I were examined for the presence of markers of HCV infection. Eleven of 13 patients (10 with EMC and 1 with type I cryoglobulinemia) had anti-HCV antibodies (as determined by a second generation anti-HCV assay) and HCV-RNA in plasma or serum. HCV-RNA was also detected in liver biopsies of five patients. Genotyping showed that HCV genotype 1 was found in 10 of 11 patients with HCV-RNA (9 genotype 1b and 1 genotype 1a) and only one patient had HCV genotype 2. However, a similar high prevalence of genotype 1b (100%) was found in a group of 14 consecutive patients with chronic hepatitis C, who had no clinical evidence of cryoglobulinemia. Concomitant infection was present in three patients with genotypes 2, 3 and 4, respectively. These findings stress the high prevalence of HCV infection in patients with EMC and further study shows that a difference in genotype prevalence was not found between HCV-related EMC and chronic hepatitis C without clinical manifestations of EMC. © 1994 Wiley-Liss, Inc. 相似文献
50.
Dou Q; Tarnuzzer RW; Williams RS; Schultz GS; Chegini N 《Molecular human reproduction》1997,3(11):1005-1014