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   7320篇
  免费   548篇
  国内免费   7篇
耳鼻咽喉   46篇
儿科学   187篇
妇产科学   134篇
基础医学   1233篇
口腔科学   142篇
临床医学   647篇
内科学   1248篇
皮肤病学   139篇
神经病学   1249篇
特种医学   232篇
外科学   748篇
综合类   67篇
一般理论   1篇
预防医学   595篇
眼科学   119篇
药学   579篇
中国医学   11篇
肿瘤学   498篇
  2022年   71篇
  2021年   114篇
  2020年   82篇
  2019年   86篇
  2018年   149篇
  2017年   106篇
  2016年   150篇
  2015年   154篇
  2014年   228篇
  2013年   264篇
  2012年   396篇
  2011年   423篇
  2010年   274篇
  2009年   240篇
  2008年   352篇
  2007年   380篇
  2006年   382篇
  2005年   345篇
  2004年   269篇
  2003年   285篇
  2002年   297篇
  2001年   160篇
  2000年   174篇
  1999年   138篇
  1998年   91篇
  1997年   82篇
  1996年   55篇
  1995年   56篇
  1994年   59篇
  1992年   94篇
  1991年   100篇
  1990年   99篇
  1989年   80篇
  1988年   87篇
  1987年   74篇
  1986年   79篇
  1985年   74篇
  1984年   64篇
  1983年   67篇
  1982年   60篇
  1980年   57篇
  1979年   78篇
  1978年   66篇
  1977年   65篇
  1976年   54篇
  1974年   59篇
  1973年   55篇
  1972年   61篇
  1971年   55篇
  1968年   49篇
排序方式: 共有7875条查询结果,搜索用时 46 毫秒
1.
Serum levels of Epinephrine (E), norepinephrine (NE), heart rate (HR), skin conductance reaction (SCR) and skin conductance level (SCL) were measured in schizophrenic, endogenous depressed and anxiety patients as well as in normal controls. Conditions were rest, noise and a mental arithmetic (MA) task. Schizophrenic and depressed patients had an attenuated HR response to MA. Moreover, Schizophrenic patients also had higher NE base level and the highest NE secretion during noise. Anxiety and depressed patients showed significantly lower phasic electrodermal activity (SCR) throughout the whole trial, exclusively anxiety patients had significantly higher tonic electrodermal activity (SCL). These findings indicate that autonomous reactions discriminate between patient groups and controls as well as between each other.  相似文献   
2.
Thiopental-induced EEG beta activity was analyzed both visually and by computer in 33 patients with complex partial epilepsy. Studies were done in 16 patients with depth electrodes in limbic structures and 17 patients with scalp and sphenoidal electrodes. The percentage of drug-induced change in beta activity was quantified by computer using spectral analysis. The statistical significance of asymmetries between homologous sites in the amount of change was determined. The spatial distribution of significant asymmetries was used for localization and compared with the results of independent visual analysis of the thiopental EEG. Concordance between computer and visual evaluation occurred in 10 of 17 scalp/sphenoidal and 10 of 16 depth electrode tests. The accuracy of visual and computer localization was determined by comparing them with locus of itcal EEG onset, interictal spikes, and positron emission tomography. In scalp/sphenoidal studies, computer analysis indicating asymmetry appeared more likely to correlate with independent clinical criteria than visual analysis. In depth studies the reverse appeared to be true. Scalp/sphenoidal tests yielded positive results in 25-30% of patients whereas depth electrode tests were positive in 50-70% of patients. The results indicate that computer analysis of surface thiopental tests is an accurate and useful supplement to visual evaluation of these tests.  相似文献   
3.
4.
5.
6.
The determination of penetration pathways of topically applied substances into the skin is the subject of several investigations. Recently, follicular penetration has become a major focus of interest. To date, a direct, non-invasive quantification of the amount of topically applied substance penetrated into the follicles had not been possible. The development of such a method was the aim of this study. Therefore, the advantages of both stripping techniques, tape stripping and cyanoacrylate skin surface biopsy, were combined and evaluated. Tape stripping was used to remove the part of the stratum corneum that contained the topically applied dye. Subsequently, the follicular contents were ripped off by cyanoacrylate skin surface biopsy. The combined method termed "differential stripping" was evaluated in vitro and in vivo , and the amount of topically applied fluorescent dye penetrated into the hair follicles was quantified after different penetration times. After 30 min, 5% of the recovered concentration of sodium fluorescein was found in the follicular infundibula, where it was still detectable after 48 h. Altogether, the results of this investigation revealed that differential stripping is a new method that can be used to study the penetration of topically applied substances into the follicular infundibula non-invasively and selectively.  相似文献   
7.
The activity of stereoisomeric [1,2-bis(3-hydroxyphenyl)ethylenediamine] dichloroplatinum(II)-complexes (1-PtCl2,R,S; 2-PtCl2, R,R/S,S; 3-PtCl2, R,R; 4-PtCl2, S,S) on several tumor models (MDA-MB 231 breast cancer cell line; P 388 leukemia, mouse; L 1210 leukemia, mouse; L 5222 leukemia, rat; Ehrlich ascites tumor, mouse--wildtype; cisplatin-, etoposide-, cyclophosphamide-, and daunomycin-resistant, resp.) is described. For comparison the analogous [1,2-bis(4-hydroxyphenyl)ethylendiamine]dichloroplatinum (II)-complexes (5-PtCl2, R, S; 6-PtCl2, R,R/S,S; 7-PtCl2, R,R; 8-PtCl2, S,S) and cisplatin are used. 1-PtCl2 to 4-PtCl2 (OH in 3,3'-positions) show their maximum antitumor effect at lower doses than 5-PtCl2 to 8-PtCl2 (OH in 4,4'-positions). 2-PtCl2 and 6-PtCl2 (R,R/S,S) are more active than 1-PtCl2 and 5-PtCl2 (R,S). 4-PtCl2 and 8-PtCl2 (S,S) are superior to 3-PtCl2 and 7-PtCl2 (R,R). On the L 5222 leukemia 2-PtCl2 (R,R/S,S), 4-PtCl2 (S,S) and 8-PtCl2 (S,S) markedly surpass cisplatin. Strong effects are produced by 2-PtCl2 to 4-PtCl2 on the Ehrlich ascites tumor (wildtype, cisplatin-, etoposide-, cyclophosphamide-, and daunomycin-resistant, resp.). The combination of 4-PtCl2 with cisplatin results in a weakly synergistic effect.  相似文献   
8.
We present a case of volar luxation of the scaphotrapezial bone, in which radiographs suggested luxation of the scaphoid, but unclear relations to the other carpal bones. Computer tomographic reconstruction showed an isolated scaphotrapezial luxation. This was treated by closed reduction and a plaster cast, after which the patient regained normal function of her wrist.  相似文献   
9.
10.
During the development of a silicone rubber implant for the delivery of estradiol 17-beta some batches of implants made from a certain lot of commercial estradiol inexplicably developed surface crystals of estradiol after several days of storage. An impurity profile was obtained for 28 lots of estradiol by a newly developed HPLC method. One or more impurities may have had a role in the spontaneous crystal growth on the surface of the implants, because the one lot of estradiol that initially had surface crystals on aging produced acceptable implants after multiple recrystallizations. Attempts to isolate suspected impurities for characterization were unsuccessful. During the manufacture of the implants, temperatures sufficient to melt the estradiol (mp, 173-179 degrees C) were used. It was expected that, upon implant cooling, melted impure estradiol would form a thermodynamically more active (i.e., noncrystalline) physical form. This metastable form could have migrated to the implant surface, where ambient conditions favored crystallization. Because melted estradiol of a higher purity tended to crystallize more readily, it was less likely to form a glass upon cooling. The phenomenon of surface crystallization was limited to one lot of estradiol with the highest level of impurities. Data from differential scanning calorimetry studies supported this conclusion.  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