全文获取类型
收费全文 | 15855篇 |
免费 | 962篇 |
国内免费 | 240篇 |
专业分类
耳鼻咽喉 | 131篇 |
儿科学 | 374篇 |
妇产科学 | 880篇 |
基础医学 | 1957篇 |
口腔科学 | 328篇 |
临床医学 | 1832篇 |
内科学 | 3382篇 |
皮肤病学 | 305篇 |
神经病学 | 1154篇 |
特种医学 | 724篇 |
外科学 | 2020篇 |
综合类 | 303篇 |
一般理论 | 8篇 |
预防医学 | 828篇 |
眼科学 | 437篇 |
药学 | 1172篇 |
1篇 | |
中国医学 | 126篇 |
肿瘤学 | 1095篇 |
出版年
2023年 | 69篇 |
2022年 | 199篇 |
2021年 | 359篇 |
2020年 | 157篇 |
2019年 | 316篇 |
2018年 | 425篇 |
2017年 | 255篇 |
2016年 | 287篇 |
2015年 | 450篇 |
2014年 | 548篇 |
2013年 | 779篇 |
2012年 | 1107篇 |
2011年 | 1181篇 |
2010年 | 771篇 |
2009年 | 639篇 |
2008年 | 882篇 |
2007年 | 968篇 |
2006年 | 844篇 |
2005年 | 821篇 |
2004年 | 731篇 |
2003年 | 638篇 |
2002年 | 623篇 |
2001年 | 566篇 |
2000年 | 537篇 |
1999年 | 393篇 |
1998年 | 185篇 |
1997年 | 176篇 |
1996年 | 162篇 |
1995年 | 139篇 |
1994年 | 108篇 |
1993年 | 105篇 |
1992年 | 189篇 |
1991年 | 168篇 |
1990年 | 128篇 |
1989年 | 161篇 |
1988年 | 136篇 |
1987年 | 113篇 |
1986年 | 96篇 |
1985年 | 85篇 |
1984年 | 65篇 |
1983年 | 44篇 |
1982年 | 52篇 |
1981年 | 37篇 |
1980年 | 32篇 |
1979年 | 48篇 |
1978年 | 28篇 |
1977年 | 38篇 |
1976年 | 48篇 |
1975年 | 37篇 |
1973年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Characterization of the structural elements in lipid A required for binding of a recombinant fragment of bactericidal/permeability-increasing protein rBPI23. 总被引:2,自引:0,他引:2 下载免费PDF全文
H Gazzano-Santoro J B Parent P J Conlon H G Kasler C M Tsai D A Lill-Elghanian R I Hollingsworth 《Infection and immunity》1995,63(6):2201-2205
Both human bactericidal/permeability-increasing protein (BPI) and a recombinant amino-terminal fragment of BPI (rBPI23) have been shown to bind with high affinity to the lipid A region of lipopolysaccharide (LPS) (H. Gazzano-Santoro, J. B. Parent, L. Grinna, A. Horwitz, T. Parsons, G. Theofan, P. Elsbach, J. Weiss, and P. J. Conlon, Infect. Immun. 60:4754-4761, 1992). In the present study, lipid A preparations derived from bacterial LPS as well as synthetic lipid A's and various lipid A analogs were used to determine the structural elements required for rBPI23 binding. rBPI23 bound in vitro to a variety of synthetic and natural lipid A preparations (both mono- and diphosphoryl forms), including lipid A's prepared from Escherichia coli and Salmonella, Neisseria, and Rhizobium species. Binding does not require that the origin of negative charge be phosphate, since rBPI23 bound with high affinity to lipid A's isolated from Rhizobium species that contain carboxylate (Rhizobium trifolii) or sulfate (Rhizobium meliloti) anionic groups and lack phosphate. Lipid A acyl chains are important, since rBPI23 did not bind to four synthetic variants of the beta(1-6)-linked D-glucosamine disaccharide lipid A head group, all devoid of acyl chains. rBPI23 also bound weakly to lipid X, a monosaccharide lipid precursor of LPS corresponding to the reducing half of lipid A. Lipid IVA, a precursor identical to E. coli lipid A except that it lacks the 2' and 3' acyl chains, was the simplest structure identified in this study that rBPI23 bound with high affinity. These results demonstrate that rBPI23 has a binding specificity for the lipid A region of LPS and binding involves both electrostatic and hydrophobic components. 相似文献
72.
Chia-Ying Liu Chih-Cheng Lai Hsiu-Tzy Chiang Min-Chi Lu Ling-Fang Wang Tsai-Ling Tsai Mei-Yu Kang Yi-Ni Jan Yi-Ting Lo Wen-Chien Ko Shu-Hui Tseng Chun-Ming Lee Po-Ren Hsueh 《Journal of microbiology, immunology, and infection》2019,52(1):62-74
Background/purpose
This study investigated the distribution and persistence of multidrug resistant organisms (MDROs) including methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacteriaceae (CRE), carbapenem-resistant Pseudomonas aeruginosa (CRPA), and multidrug-resistant Acinetobacter baumannii (MDRAB) in six long-term care facilities (LTCFs).Methods
We investigated the distribution of MDROs in residents of six LTCFs and their environments from January to December 2016 (intervention period). Active surveillance of colonization of MDROs was performed by culturing rectal and nasal swab samples from the residents every three months. Multilocus sequence typing (MLST) was conducted, and genes for panton-valentine leukocidin (PVL) from MRSA isolates were determined.Results
A total of 521 samples were positive for MDROs, and MRSA was the most common organism (65.1%), followed by MDRAB (11.3%), carbapenem-resistant Klebsiella pneumoniae (11.1%), carbapenem-resistant Escherichia coli (4.6%), and carbapenem-resistant P. aeruginosa (2.1%, n = 11). By a linear regression model, positive MRSA isolates from the environment were found to be statistically significant and associated with the number of colonized LTCF residents (p = 0.01), while the timing of the surveillance culture was not (p = 0.227). The main MLST types associated with PVL-production were sequence type (ST) 59, (40.0%, 24/60), ST30 (21.4%, 3/14), ST8 (87.5%, 14/16), and ST45 (3.6%, 1/28). The susceptibility rates of tetracycline (96.7%), trimethoprim-sulfamethoxazole (96.7%), and ciprofloxacin (81.7%) were statistically significant and higher in MRSA ST59, compared to the rates in MRSA ST45 isolates.Conclusions
MRSA was the most commonly colonized MDRO, both in the LTCF residents and in the environment, followed by MDRAB and carbapenem-resistant K. pneumoniae. 相似文献73.
Katherine H. Tsai Andrew L. Moskowitz Roxanna E. Lynch Eric Daleiden Charles Mueller Jennifer L. Krull 《Journal of clinical child and adolescent psychology》2019,48(2):S72-S78
We investigated whether a service-planning document outlining recommendations for what providers should address in treatment (i.e., targets) and the associated clinical techniques they should employ (i.e., practices) influenced the targets and practices that providers reported actually implementing during the subsequent treatment episode. Participants included 94 youths ages 4 to 17 (M = 13.57, SD = 3.59) who received community-based mental health services from the Hawai'i Child and Adolescent Mental Health Division. Data on targets and practices were compared across initial Mental Health Treatment Plans and Monthly Treatment and Progress Summaries. Data were analyzed using two-level, generalized mixed effects models with two-way cross-classification or linear mixed effects models. Providers were more likely to report the use of targets and practices in treatment if they were included within the treatment plan. In addition, the more closely targets addressed during treatment followed the recommended targets from the treatment plan, the more closely implemented practices followed the recommended practices listed in the treatment plan. Furthermore, as providers shifted their focus to different targets, a shift in their use of practices was also evident over time. Last, practices for which there is demonstrated efficacy for particular targets were more likely to be used. Service planning documents appear to help organize care; however, results also suggest possible limitations to the current system. These findings highlight potential areas for improvement in planning and care delivery. 相似文献
74.
Insoluble immune complex-stimulated neutrophil leukotriene B4 production is dependent on Fc gamma RII and Fc gamma RIII and independent of pertussis toxin-sensitive signal transduction pathways. 下载免费PDF全文
E. Crockett-Torabi C. W. Smith J. R. Kateley R. Patterson P. Tsai J. C. Fantone 《The American journal of pathology》1992,140(3):613-620
Leukotriene B4 (LTB4) release initiated by interaction of immune complexes (ICs) with Fc gamma RII and Fc gamma RIII receptors on human neutrophils was studied using well-defined complexes. Immune complexes consisting of polyclonal rabbit antibody to human albumin were prepared at equivalence (insoluble complex) and at five times antigen excess (soluble complex). Incubation of human neutrophils with soluble and insoluble ICs led to the synthesis of LTB4 from endogenous arachidonic acid (AA). LTB4 release induced by ICs was markedly inhibited by monoclonal antibodies against either Fc gamma RII or Fc gamma RIII receptor. Treatment of neutrophils with pertussis toxin significantly inhibited the release of LTB4 induced by soluble ICs. However pertussis toxin treatment minimally inhibited the LTB4 release induced by insoluble ICs. Crosslinking of either Fc gamma RII and Fc gamma RIII receptors on neutrophil surfaces induced LTB4 release. This is the first experimental observation showing that both Fc gamma RII and Fc gamma RIII directly induce neutrophil LTB4 metabolism in the absence of exogenous AA. These studies also suggest the involvement of novel pertussis toxin insensitive signal transduction pathways in insoluble ICs stimulation of neutrophils. 相似文献
75.
P Y Liu Y J Lau B S Hu J M Shir M H Cheung Z Y Shi W S Tsai 《Journal of clinical microbiology》1994,32(8):1935-1938
A method to characterize strains of Serratia marcescens based on the PCR amplification of enterobacterial repetitive intergenic consensus sequences has been developed. The PCR fingerprints were generated from boiled supernatants prepared directly from bacterial colonies without the need for DNA extraction. The technique was applied to isolates obtained during an outbreak of pneumonia from seven mechanically ventilated patients, and its result indicated that the outbreak was due to the spread of two epidemic strains. This technique was validated by comparison with rRNA gene restriction analysis. There was complete concordance between these two techniques in discriminating the outbreak-related strains from epidemiologically unrelated isolates. Typing with both biochemical profile and antibiogram profile, though simple, was found to be less reliable than genotyping. The results show that this enterobacterial repetitive intergenic consensus PCR provides a rapid and simple means of typing S. marcescens isolates for epidemiologic studies. 相似文献
76.
Summary Interferon (IFN) was measured in serum and cerebrospinal fluid (CSF) of dogs after experimental (intranasal) infection with different strains of virulent canine distemper virus (CDV). Viral strains employed produce neurological changes in dogs that range from acute inflammatory to subacute, delayed demyelinating encephalomyelitis. With few exceptions, first appearance of serum-IFN correlated with the first elevated body temperature 4 days post-infection (p.i.). By 16 days p.i. IFN had disappeared from the serum of all infected dogs. In contrast, IFN was constantly detectable in CSF in dogs with CDV infection of the central nervous system (CNS). It was first detected 5 days p.i., was continuously detectable during the variable preclinical phase and into the period when signs of acute or delayed encephalomyelitis were evident. Dogs from which CDV would be retrieved from CNS tissue at necropsy always had CSF-IFN (up to 56 days p.i.). In contrast, dogs that recovered from infection, substantiated at necropsy by minimal, resolving CNS lesions and non-detectable virus, had IFN in CSF demonstrable for only a brief post-inoculation period. CSF-IFN appears to be a valid marker for CDV persistence in the canine CNS and may have broader applications.With 3 Figures 相似文献
77.
Hwang JL Huang LW Hsieh BC Tsai YL Huang SC Chen CY Hsieh ML Chen PH Lin YH 《Human reproduction (Oxford, England)》2003,18(1):45-49
BACKGROUND: The introduction of GnRH antagonists such as cetrorelix acetate has made possible the simplification of ovarian stimulation. However, the most effective protocol for their administration has not yet been clearly defined. METHODS: Forty women with male-factor infertility undergoing 40 ICSI cycles were included in the study. Clomiphene citrate at 100 mg a day was given from cycle day 3 through day 7. hMG at 150 IU was given on cycle days 4, 6 and 8, and was adjusted from day 9 according to the follicular and hormone responses. Cetrorelix acetate at 2.5 mg was administered when the leading follicle reached 14 mm. The remaining 0.5 mg was divided into two 0.25 mg injections for possible later use. Serum FSH, LH, estradiol and progesterone levels were measured daily from the day of cetrorelix acetate injection until hCG was given. RESULTS: Serum LH level was suppressed effectively for 4 days. Four patients (10%) needed one or two additional injections of 0.25 mg cetrorelix acetate. No premature LH surge was detected in any of the women treated. Sixteen women became pregnant (40%), of which 14 pregnancies (35%) were ongoing at the time of writing. CONCLUSIONS: This study demonstrates that this new protocol is feasible for couples with male-factor infertility undergoing ICSI. 相似文献
78.
Bilateral simultaneous tubal sextuplets: pregnancy after in-vitro fertilization--embryo transfer following salpingectomy 总被引:2,自引:1,他引:2
The presence of a damaged tube has been suggested in recent studies to have
a negative effect on in-vitro fertilization (IVF) outcome. Performing
bilateral salpingectomy prior to IVF to maximize pregnancy rates may also
result in unnecessary surgery. This case is also an example of the
occurrence of interstitial pregnancy after salpingectomy. This unusual type
of ectopic pregnancy must be kept in mind when evaluating a patient
suspected of a possible early abnormal gestation after assisted
reproductive technolologies.
相似文献
79.
The roles of the ionic currents in the firing of potential bursts elicited by d-amphetamine in central snail neurons were studied in the identified RP4 neuron of the African snail, Achatina fulica Ferussac, using the two-electrode voltage-clamp method. Oscillations of membrane potential bursts were elicited by d-amphetamine. The action potential bursts elicited by d-amphetamine decreased following intracellular injection of either EDTA or magnesium, or extracellular application of lanthanum. Voltage-clamped studies revealed that d-amphetamine decreased the fast Na(+), Ca(2+) and transient outward K(+) currents of the RP4 neuron. It also decreased the steady-state K(+) current and elicited a negative slope resistance in the steady-state I-V curve between -50 and -10 mV. The amplitude of negative slope resistance was decreased if either Na(+)-free saline or Co(2+)-substituted Ca(2+)-free saline was perfused. d-Amphetamine did not increase the amplitude of the slowly inactivating Ca(2+) current or the persistent Na(+) currents of RP4 neuron. Tetraethylammonium, a blocker of the delayed outward K(+) current, elicited action potential bursts and negative slope resistance in the RP4 neuron, while 4-aminopyridine, an inhibitor of transient outward K(+) current (I(A)), did not.These results demonstrate that the delayed outward K(+) current and the negative slope resistance in steady-state I-V curve elicited by d-amphetamine may be responsible for the action potential bursts in central snail neurons elicited by d-amphetamine. 相似文献
80.
Wang M Tzeng TY Fung CY Ou WC Tsai RT Lin CK Tsay GJ Chang D 《Journal of virological methods》1999,78(1-2):171-176
The immunoreactivity of human anti-JC virus (JCV) serum against the major capsid protein VP1 of JCV was analyzed by Western blot, dot blot, and hemagglutination inhibition (HAI) assays. JCV-positive human serum reacted with native but not denatured JCV major capsid protein VP1, as demonstrated by dot blot and Western blot. Rabbit antiserum raised against native JCV capsid had immunoreactivities similar to those of human anti-JCV serum. These results indicate that the antigenecity of native and denatured JCV VP1 is different. In addition, both JCV-positive human serum and rabbit antiserum raised against native JCV capsid protein inhibited the hemagglutination activity of JCV capsid particles. In contrast, rabbit antiserum raised against denatured JCV VP1 did not inhibit hemagglutination. These findings reveal that denaturation may alter the antigenic epitopes of JCV VP1. Therefore, keeping the JCV capsid protein native appears to be essential for serological or other immunological analyses of the virus. 相似文献