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   3493篇
  免费   360篇
  国内免费   7篇
耳鼻咽喉   21篇
儿科学   102篇
妇产科学   101篇
基础医学   546篇
口腔科学   84篇
临床医学   408篇
内科学   584篇
皮肤病学   80篇
神经病学   195篇
特种医学   178篇
外科学   480篇
综合类   326篇
预防医学   223篇
眼科学   46篇
药学   270篇
  1篇
中国医学   6篇
肿瘤学   209篇
  2021年   47篇
  2020年   25篇
  2019年   44篇
  2018年   59篇
  2017年   28篇
  2016年   34篇
  2015年   75篇
  2014年   99篇
  2013年   109篇
  2012年   118篇
  2011年   166篇
  2010年   123篇
  2009年   110篇
  2008年   176篇
  2007年   144篇
  2006年   160篇
  2005年   157篇
  2004年   161篇
  2003年   131篇
  2002年   120篇
  2001年   119篇
  2000年   110篇
  1999年   113篇
  1998年   61篇
  1997年   54篇
  1996年   59篇
  1995年   57篇
  1994年   44篇
  1993年   35篇
  1992年   72篇
  1991年   79篇
  1990年   68篇
  1989年   70篇
  1988年   82篇
  1987年   68篇
  1986年   62篇
  1985年   65篇
  1984年   58篇
  1983年   39篇
  1982年   38篇
  1981年   26篇
  1980年   24篇
  1979年   39篇
  1978年   26篇
  1977年   22篇
  1976年   26篇
  1975年   20篇
  1974年   20篇
  1972年   23篇
  1971年   20篇
排序方式: 共有3860条查询结果,搜索用时 31 毫秒
1.
BACKGROUND: The present study was aimed to define the gender ratio, familial occurrence, age of onset, precipitating factors, clinical types, nail and joint involvement of psoriasis in childhood and adolescence in Turkey. METHODS: A total of 61 children with psoriasis under 18 years old were evaluated retrospectively, for age, gender, age of disease onset, family history, concomitant disease, the clinical type of psoriasis, clinical localization, nail and joint involvement and treatment modalities. RESULTS: Of the patients, 23 (37.70%) were boys and 38 (62.30%) were girls. Mean age was 9.28 +/- 4.02 years in girls and 11.18 +/- 3.85 years in boys (9.96 +/- 4.03 years in all children). Mean age at the onset of the disease was 6.81 +/- 4.11 years in girls and 7.03 +/- 4.28 years in boys (6.89 +/- 4.14 years in all patients). In 14 (23%) cases, a positive family history was detected. The most frequent probable triggering factors were upper respiratory tract infections (14.8%) and positive throat culture for A group ss-hemolytic streptococcus (21.3%). Frequency of emotional stress and psychiatric morbidity were 54% and 9.8%, respectively. The most frequent localizations at onset were trunk (44.3%), extremities (54.0%), and scalp (36.0%). Three children (4.9%) had a history of dissemination from psoriatic diaper rash. In total, 51 (83.6%) patients presented with psoriasis vulgaris, eight (13.1%) with generalized pustular psoriasis, and the remaining two (3.3%) with erythrodermic psoriasis. CONCLUSION: The incidence of psoriasis among dermatological patients in childhood and adolescence was 3.8%. The disease tends to appear earlier in girls than boys. The authors suggested that stress and upper respiratory infections are the most important triggering factors in childhood and adolescence psoriasis.  相似文献   
2.
3.
In brain regions containing noradrenergic (NA) cell bodies or terminals, DSP-4 induces changes in the activity of catecholamine-synthesizing enzymes which suggest that central NA neurons are lesioned by this neurotoxin. In contrast, the lack of change in the same enzymatic activities in an area containing mostly adrenergic (A) neurons (C2 region), favors the hypothesis of a resistance of the A neurons to DSP-4. Furthermore, the enzymatic changes observed in peripheral organs suggest a peripheral activation of the NA cell bodies in response to lesioning of the sympathetic terminals by DSP-4.  相似文献   
4.
The behavioral effects of the antidepressants nomifensine, diclofensine, bupropion, and imipramine were examined using a cocaine substitution drug self-administration procedure in baboons and a cocaine drug discrimination procedure in rats. Intravenous self-administration of the antidepressants was examined in baboons under conditions in which baseline responding was maintained by intravenous injections of cocaine HCl (0.32 mg/kg/injection). Drug was available under a fixed-ratio 80-response or 160-response schedule of intravenous injection. Each drug injection was followed by a 3-h time-out allowing a maximum of eight injections per day. The antidepressants or their vehicles were substituted for cocaine for a period of 15 days, followed by a return to the cocaine baseline. Nomifensine, diclofensine, and bupropion all maintained self-administration behavior at levels above those maintained by their respective vehicles. Some doses of nomifensine, diclofensine, and bupropion maintained levels of behavior similar to those maintained under baseline cocaine conditions. High doses of imipramine maintained levels of behavior above those maintained by its vehicle, but the amount of behavior maintained under these conditions was extremely small. In a second experiment rats were trained to discriminate 32 µmol/kg cocaine (IP 10 min presession) from no drug in a two-lever food reinforced drug discrimination procedure in which responding on one lever was reinforced following ten consecutive responses when the session was preceded by cocaine administration, while responding on the other lever was similarly reinforced in the absence of cocaine pretreatment. Cocaine, nomifensine, diclofensine, and bupropion all dose-dependently occasioned cocaine-appropriate responding. Imipramine did not occasion cocaine-appropriate responding over a range of behaviorally active doses.  相似文献   
5.
6.
7.
Linomide (N-phenylmethyl-1,2-dihydro-4-hydroxyl-1-methyl-2-oxo-quinoline-3- carboxamide) is a quinoline 3-carboxamide which previously has been demonstrated to produce immunomodulator and antitumor effects when given in vivo. To test the possible antitumor effects of linomide against prostatic cancers, rats bearing five distinct Dunning R-3327 rat prostatic cancer sublines were treated daily with i.p. injections of linomide. These studies demonstrated that linomide has a reproducible antitumor effect against all of the prostatic cancers tested regardless of their growth rate, degree of morphologic differentiation, metastatic ability, or androgen responsiveness. This antitumor effect is observed only in vivo, not in vitro, and involves a cytotoxic response of the prostatic cancer cells. This cytotoxic response results in the retardation of the growth rate (i.e., increased tumor volume doubling time) of primary prostatic cancers and in metastatic lesions. Linomide's growth retardation is reversible, and thus continuous daily treatment with linomide is required for maximal antitumor response. Pretreatment of rats with linomide before tumor inoculation has no effect in addition to that produced by initiating linomide treatment at the time of tumor inoculation. No enhancement of either natural killer cell number or natural killer cell cytotoxic activity is induced by linomide treatment in the tumor-bearing rats. In addition, depletion of natural killer cell activity via injections of asialo-GM1 antiserum does not prevent the antitumor effects of linomide in vivo. Likewise, the antitumor effects of linomide are also produced in prostatic cancer-bearing athymic nude rats. These results suggest that the requirement for host involvement in the antitumor effects of linomide against rat prostatic cancers may involve both immune and nonimmune host mechanism(s) (e.g., antiangiogenesis).  相似文献   
8.
9.
10.
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