首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7509篇
  免费   610篇
  国内免费   37篇
耳鼻咽喉   70篇
儿科学   159篇
妇产科学   228篇
基础医学   1057篇
口腔科学   95篇
临床医学   796篇
内科学   1637篇
皮肤病学   54篇
神经病学   500篇
特种医学   260篇
外科学   1247篇
综合类   143篇
一般理论   6篇
预防医学   487篇
眼科学   246篇
药学   518篇
中国医学   19篇
肿瘤学   634篇
  2024年   11篇
  2023年   71篇
  2022年   121篇
  2021年   237篇
  2020年   130篇
  2019年   209篇
  2018年   259篇
  2017年   182篇
  2016年   169篇
  2015年   212篇
  2014年   311篇
  2013年   376篇
  2012年   562篇
  2011年   583篇
  2010年   360篇
  2009年   270篇
  2008年   447篇
  2007年   464篇
  2006年   462篇
  2005年   445篇
  2004年   427篇
  2003年   402篇
  2002年   367篇
  2001年   209篇
  2000年   131篇
  1999年   122篇
  1998年   75篇
  1997年   52篇
  1996年   38篇
  1995年   39篇
  1994年   33篇
  1993年   23篇
  1992年   45篇
  1991年   49篇
  1990年   30篇
  1989年   32篇
  1988年   28篇
  1987年   28篇
  1986年   23篇
  1985年   13篇
  1984年   13篇
  1983年   13篇
  1981年   5篇
  1980年   8篇
  1979年   13篇
  1978年   5篇
  1977年   9篇
  1976年   6篇
  1975年   8篇
  1974年   6篇
排序方式: 共有8156条查询结果,搜索用时 15 毫秒
11.
A lung carcinoma with tumor involving more than one lobe or in close proximity to the mainstem bronchus often requires pneumonectomy for surgical cure. Inflammation, bulky tumors, and dense adhesions limit the operative field of vision and may result in the abandonment of procedures with potential for complete extirpation. This case illustrates the utility of thoracoscopy in visualization of the hilum and other neurovascular structures in a patient with a proximal tumor and dense intrathoracic adhesions. Successful resection was made possible by use of combined open and thoracoscopic modalities.  相似文献   
12.
Neurotrophic factors have been demonstrated to prevent the development of peripheral neuropathy in animal models, but the therapeutic use of these factors in human disease has been limited by the short serum half-life and dose-limiting side effects of these potent peptides. We used peripheral subcutaneous inoculation with a replication-incompetent, genomic herpes simplex virus-based vector containing the coding sequence for neurotrophin-3 to transduce sensory neurons of the rat dorsal root ganglion in vivo, and found that expression of neurotrophin-3 from the vector protected peripheral sensory axons from neuropathy induced by intoxication with pyridoxine assessed by electrophysiological (foot sensory response amplitude, and conduction velocity, and H-wave), histological (nerve morphology and morphometry), and behavioral measures of proprioceptive function. In vivo gene transfer using herpes simplex virus vectors provides a unique option for treatment of diseases of the sensory peripheral nervous system.  相似文献   
13.
Mosaic ring 12p and total anomalous pulmonary venous return   总被引:1,自引:0,他引:1  
An infant born with total anomalous pulmonary venous return (TAPVR) was found to have an extra chromosome present as a small ring. Spectral karyotyping and FISH analysis identified the material as a duplication involving the short arm of chromosome 12. Previous cases describing a variety of cytogenetic abnormalities that have been associated with TAPVR are reviewed along with prior cases of duplication 12p with their associated findings. We believe ours is the first case to report the occurrence of mosaic ring 12p and its association with TAPVR.  相似文献   
14.
Atypical sexual behavior during sleep   总被引:5,自引:0,他引:5  
OBJECTIVE: This article reports a case series of atypical sexual behavior during sleep, which is often harmful to patients or bed partners. METHODS: Eleven subjects underwent clinical evaluation of complaints of sleep-related atypical sexual behavior. Complaints included violent masturbation, sexual assaults, and continuous (and loud) sexual vocalizations during sleep. One case was a medical-legal case. Sleep logs, clinical evaluations, sleep questionnaires, structured psychiatric interviews, polysomnography, actigraphy, home electroencephalographic monitoring during sleep, and clinical electroencephalographic monitoring while awake and asleep were used to determine clinical diagnoses. RESULTS: Atypical sexual behaviors during sleep were associated with feelings of guilt, shame, and depression. Because of these feelings, patients and bed partners often tolerated the abnormal behavior for long periods of time without seeking medical attention. The following pathologic sleep disorders were demonstrated on polysomnography: partial complex seizures, sleep-disordered breathing, stage 3 to 4 non-rapid eye movement (REM) sleep parasomnias, and REM sleep behavior disorder. These findings were concurrent with morning amnesia. CONCLUSIONS: The atypical behaviors were related to different syndromes despite the similarity of complaints from bed partners. In most cases the disturbing and often harmful symptoms were controlled when counseling was instituted and sleep disorders were treated. In some cases treatment of seizures or psychiatric disorders was also needed. Clonazepam with simultaneous psychotherapy was the most common successful treatment combination. The addition of antidepressant or antiepileptic medications was required in specific cases.  相似文献   
15.
16.
Lo SK  Woo PC  Yuen KY 《Archives of virology》1999,144(3):601-612
Summary.  Nested polymerase chain reaction (PCR) amplifying the morphological transforming region II (mtrII) of cytomegalovirus (CMV) has been shown to be useful in the detection of CMV DNA in bone marrow transplant (BMT) recipients. However, there has never been any report on mutation hot spots and subtypes of this open reading frame. Using primers derived from sequences upstream and downstream of mtrII (ORF 79), CMV DNA from peripheral blood leukocytes (PBL) and conventional CMV culture of 16 BMT recipients were amplified by PCR, cloned into pUC118, and sequenced. The amino acid sequences were predicted using the standard triplet code. The DNA sequences obtained from direct amplification of CMV in PBL obtained from the 16 patients were 100% identical to the corresponding ones obtained by amplification of CMV DNA extracted from conventional CMV culture. Within mtrII (ORF 79), hot spot single base mutations were observed at positions +40 (G→A), +123 (A→G), +213 (T→C), and +219 (T→C). However, because of third base degeneracy, only amino acid 14 was changed from valine to isoleucine in the predicted protein of 13 patients. This corresponded to the hot spot mutation at position +40 (GTC→ATC), while the rest were silent mutations. An insertion of 3 bases (ACG) was observed in the CMV DNA of 10 patients at positions +91 to +93, leading to a threonine insertion at amino acid 31 in these patients. For patient no. 147 there was a 65 bp deletion in the CMV DNA amplified later in the course of BMT as compared with that early in the course. This gave rise to a frame shift mutation and a change of more than 70% in the predicted amino acid sequence of the protein. Accepted October 14, 1998 Received May 20, 1998  相似文献   
17.
Streptococcus pyogenes protein H (sph) is an immunoglobulin-binding protein present in the Mga regulon of certain M1 serotype isolates. Although sph is present in many strains, it is frequently not expressed. In this paper we show that protein H was highly expressed after bacteria were injected into the skin of mice and were recovered from the blood, kidney, or spleen at various times postinfection. The percentage of protein H-positive colonies increased with time, reaching 100% in the spleen and kidney within 24 to 72 h postinfection. The up-regulation of sph expression was also observed in a mga mutant.  相似文献   
18.
The Batho equation gives a satisfactory method to correct the dose for points in the electronic equilibrium region for a uniform slab of inhomogeneity in a photon beam. In spite of the many investigations, we believe no simple and adequate method has been found for routine clinical dose calculations which require dose correction of a small-volume inhomogeneity in an arbitrary location. In the present report, we combine the values of the two calculation types of the differential Batho method, which we have developed previously, to give a new calculated value for the scatter perturbation due to an annulus of inhomogeneity. The coefficients in the combination, which we derived from a detailed analysis of the scatter perturbation, are simple geometrical ratios. The new calculated values are in good agreement with measured values. We believe this application of the differential Batho method can provide a practical and accurate method of correcting for inhomogeneities of any size and shape in clinical dose calculations.  相似文献   
19.
Eighty-four specimens of respiratory secretions culture positive for mycobacteria (70 positive for Mycobacterium tuberculosis and 14 positive for nontuberculous mycobacteria) and 120 culture-negative specimens were evaluated by three DNA amplification techniques: a manual in-house single-tube nested PCR (nPCR) and two commercial automated assays (the Cobas Amplicor System [aPCR-h] from Roche Diagnostic Systems and the Abbott LCx Probe System [aLCx-p] from Abbott Laboratories). The overall diagnostic sensitivities of the nPCR, aPCR-h, and aLCx-p were 77.1, 84.3, and 77.1%, respectively, and the sensitivities were 57.9, 57.9, and 36.8%, respectively, for smear-negative specimens. Specimens culture positive for nontuberculous mycobacteria were negative by all three assays. Eight culture-negative specimens which were positive by one or more assays had previously been documented by culture to be positive for M. tuberculosis and were taken from patients who were treated with antituberculosis agents. Retesting of specimens negative by one assay by the other two assays revealed that each test had its unique group of negative specimens. When considering the DNA extraction and amplification steps of these assays separately, it was found that extracts from aPCR-h and aLCx-p were compatible with nPCR amplication, while the two automated assays could only amplify extracts processed with their own reagents. Limiting dilution analysis revealed that the order of analytical sensitivity was nPCR, followed by aLCx-p and then aPCR-h. Comparison of the work flow of each assay revealed that although the aPCR-h demands the least specimen handling, the turnaround time of aLCx-p is the most favorable.  相似文献   
20.
Three tests, the disk diffusion test, the double-disc synergy test and the inhibitor-potentiated disc diffusion test, were compared for their abilities to detect production of extended-spectrum beta-lactamases (ESBL) in 702 Escherichia coli and 472 Klebsiella spp. strains from four hospitals. Eleven percent E. coli and 13% Klebsiella spp. were found to produce ESBL. As an indicator of ESBL activity, the sensitivities of the five extended-spectrum beta-lactams were as follows: cefotaxime (100%), cefpodoxime (99.3%), ceftriaxone (98.6%), aztreonam (93%) and ceftazidime (57.7%) when interpreted using the National Committee for Clinical Laboratory Standards criteria. Their positive predictive values ranged from 67.8-83.8%. Both the inhibitor-potentiated disc diffusion test and the double-disc synergy test (at three inter-disc widths of 20, 25 and 30 mm) were capable of identifying all the ESBL-producers. However, at a single inter-disc width of 30 mm, the double-disc synergy test has limited sensitivity (83.8%). As a second test for confirming ESBL activity in strains with reduced susceptibility to beta-lactams, the inhibitor-potentiated disc diffusion test is therefore a simple and reliable option.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号