全文获取类型
收费全文 | 4308篇 |
免费 | 302篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 57篇 |
儿科学 | 144篇 |
妇产科学 | 70篇 |
基础医学 | 654篇 |
口腔科学 | 218篇 |
临床医学 | 383篇 |
内科学 | 880篇 |
皮肤病学 | 107篇 |
神经病学 | 474篇 |
特种医学 | 76篇 |
外科学 | 465篇 |
综合类 | 32篇 |
一般理论 | 1篇 |
预防医学 | 328篇 |
眼科学 | 39篇 |
药学 | 381篇 |
中国医学 | 1篇 |
肿瘤学 | 314篇 |
出版年
2021年 | 60篇 |
2020年 | 50篇 |
2019年 | 51篇 |
2018年 | 67篇 |
2017年 | 47篇 |
2016年 | 60篇 |
2015年 | 49篇 |
2014年 | 71篇 |
2013年 | 141篇 |
2012年 | 200篇 |
2011年 | 186篇 |
2010年 | 96篇 |
2009年 | 93篇 |
2008年 | 211篇 |
2007年 | 194篇 |
2006年 | 233篇 |
2005年 | 202篇 |
2004年 | 200篇 |
2003年 | 183篇 |
2002年 | 173篇 |
2001年 | 160篇 |
2000年 | 141篇 |
1999年 | 126篇 |
1998年 | 54篇 |
1997年 | 47篇 |
1996年 | 48篇 |
1995年 | 39篇 |
1994年 | 38篇 |
1993年 | 38篇 |
1992年 | 132篇 |
1991年 | 113篇 |
1990年 | 95篇 |
1989年 | 108篇 |
1988年 | 70篇 |
1987年 | 81篇 |
1986年 | 81篇 |
1985年 | 97篇 |
1984年 | 64篇 |
1983年 | 54篇 |
1982年 | 43篇 |
1981年 | 26篇 |
1980年 | 25篇 |
1979年 | 32篇 |
1978年 | 37篇 |
1977年 | 29篇 |
1975年 | 25篇 |
1974年 | 31篇 |
1973年 | 20篇 |
1972年 | 27篇 |
1971年 | 19篇 |
排序方式: 共有4624条查询结果,搜索用时 0 毫秒
1.
2.
3.
M Müller J Grunewald C Olgart H?glund B Dahlén A Eklund H Stridh 《The European respiratory journal》2006,28(3):513-522
The increased number of lymphocytes in airways during an asthmatic response is believed to be the result of increased recruitment of these cells. However, it is possible that a decreased apoptotic rate could also contribute to the increased number. The aim of the present study was to investigate whether allergen airway provocation influences the apoptotic phenotype of lung and peripheral blood lymphocytes (PBL) in subjects with atopic asthma. Bronchoalveolar lavage (BAL) lymphocytes and PBL from 12 asthmatic subjects previously challenged with allergen (n = 7) or saline (n = 5) were exposed to the apoptotic stimulus tributyltin (TBT) in vitro and assayed for apoptosis. Airway allergen provocation resulted in decreased sensitivity of BAL lymphocytes to TBT-induced apoptosis, with 42.2% (range 33.9-62.5%) apoptotic cells before challenge versus 23.5% (range 15.3-42.4%) after challenge, while PBL were unaffected. The increased apoptosis resistance correlated with higher numbers of Bcl-2-expressing lymphocytes. Interestingly, baseline caspase-3-like activity was significantly elevated in viable BAL lymphocytes compared with viable PBL, and was unaltered by allergen exposure. In conclusion, allergen inhalation renders bronchoalveolar lavage lymphocytes more resistant to apoptosis while peripheral blood lymphocytes were not influenced at all, indicating that the apoptotic phenotype of airway lymphocytes may play a role in asthmatic inflammation. 相似文献
4.
5.
6.
7.
Clonidine (10 micrograms X kg-1) reduced by almost 50% the increase in plasma neuropeptide (NPY)-like immunoreactivity (-LI) induced by preganglionic nerve stimulation at 8 Hz. This effect was reversed by yohimbine (1 mg X kg-1) which caused a three-fold increase of the plasma NPY-LI. Prazosin (1 mg X kg-1) had no such effect. Guanethidine (5 mg X kg-1) reduced the stimulation-evoked increase in plasma NPY-LI. It is concluded that the release of NPY-LI evoked by nerve stimulation from sympathetic nerve terminals is controlled by a presynaptic alpha 2-adrenoceptor-mediated mechanism. 相似文献
8.
Effect of nicotine, silver acetate, and ordinary chewing gum in combination with group counselling on smoking cessation.
下载免费PDF全文
![点击此处可从《Thorax》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Four hundred and ninety six smokers participated in a randomised comparison of the effect of silver acetate, nicotine, and ordinary chewing gum on smoking cessation. All were motivated to stop smoking abruptly and all had smoked at least 10 cigarettes a day for at least five years. Side effects and taste acceptability were related to outcome after six months. The participants attended nine meetings over a year, at which lectures, support, and advice about stopping smoking were given. Tobacco abstinence was confirmed by measurement of carbon monoxide in expired air. The chewing gums were used for 12 weeks. After 12 weeks there was a trend towards more abstainers in the nicotine group (59%) than in the silver acetate (50%) and ordinary (45%) chewing gum groups that was not quite significant (p = 0.07). At 26 and 52 weeks the number of cigarette abstainers was similar in the three treatment groups. Subjects in the nicotine chewing gum group had a longer mean time before relapse than those in the silver acetate and ordinary chewing gum groups. Mean success rates for all subjects combined at 12, 26, and 52 weeks were 52.8%, 39.7%, and 23.3%. The side effects of nicotine and silver acetate chewing gum were generally mild and transient, and unimportant except for mouth irritation from silver acetate, which had a negative effect on outcome, and the low taste acceptability of nicotine, which had a strong negative influence on the success rate. The results suggest a short term effect on nicotine chewing gum on smoking cessation, but the abstinence rates after one year were generally disappointing. 相似文献
9.
J T Knuiman J G Hautvast K F Zwiauer K Widhalm M Desmet G De Backer R R Rahneva V S Petrova M Dahl J Viikari 《European journal of clinical nutrition》1988,42(10):847-855
We have measured systolic and diastolic blood pressure and excretions of sodium, potassium, calcium and magnesium in groups of about 50 8- and 9-year-old boys from 19 European centres using standardized methods for the measurement of blood pressure and collection of urine, and by carrying out all analyses in one laboratory. Weight, height, pulse rate and environmental temperature were also studied. Mean systolic blood pressure ranged from 91 to 105 mm Hg and diastolic blood pressure from 51 to 66 mm Hg. Mean 24-h excretion of sodium was between 91 and 146 mmol/d, that of potassium between 29 and 60 mmol/d, that of calcium between 1.5 and 2.6 mmol/d and that of magnesium between 2.7 and 4.2 mmol/d. Mean sodium excretion tended to be lower and potassium excretion tended to be higher in the boys from the north-western parts of Europe. Relations between either systolic or diastolic blood pressure and electrolyte excretions were generally weak or absent. Most remarkable is that only the association between mean diastolic blood pressure and 24-h magnesium excretion (partial regression coefficient (b +/- s.e., -5.04 +/- 2.08 mm Hg/mmol/d) was statistically significant after adjusting for differences in creatinine excretion and environmental temperature. Mean systolic blood pressure was not significantly related with any of the variables measured. The partial regression coefficient (b +/- s.e.) for diastolic blood pressure on weight was 0.186 +/- 0.062 mm Hg/kg, on height 0.165 +/- 0.056 mm Hg/cm, on pulse rate 0.364 +/- 0.100 mm Hg/beats per min and on outside temperature -0.25 +/- 0.07 mm Hg/degrees C. 相似文献
10.
J. L. Lewis C. E. Rhoades D. E. Bice J. R. Harkema J. A. Hotchkiss D. M. Sylvester A. R. Dahl 《Anatomical record (Hoboken, N.J. : 2007)》1992,232(4):620-627
The observation of high levels of xenobiotic metabolizing enzyme activity in the olfactory mucosa has produced speculation on the functional significance of these enzymes in the nose. Hypothesized roles include protection of the nasal epithelium, lung, and other downstream tissues, and termination or modification of olfactory responses. The enzyme rhodanese metabolizes cyanide, which is a commonly inhaled toxicant and an odorant and therefore of interest to both toxicologists and olfactory neurobiologists. The cellular localization of this enzyme within the olfactory mucosa will have important consequences for its ability to protect specific cells, as well as its ability to alter the concentration of inhaled cyanide at receptors, and therefore could provide clues as to its function in this tissue. We have compared the distribution of this enzyme in two species, the rat and the cow, using immunohistochemical localization techniques employing species-specific polyclonal antisera raised in our laboratory. In the rat, rhodanese-like immunoreactivity was greatest within the apical portion of the sustentacular cells, the basal cells, and the duct cells of Bowman's glands. Very little to no reaction was observed in the acinar cells of Bowman's glands. In the cow, however, the acinar cells and duct cells of Bowman's glands showed intense immunoreactivity with little to no reaction observed in the sustentacular or basal cells. The differences in localization of rhodanese in these two species may have important implications for cell types at risk during inhalation of cyanide or organonitrile compounds metabolized to cyanide within the nasal mucosa. In addition, the difference in distribution in the two species emphasizes the importance of considering enzyme activity and localization in the determination of an appropriate animal model for study of both nasal toxicology and olfactory responsiveness in humans. 相似文献