全文获取类型
收费全文 | 2217717篇 |
免费 | 158075篇 |
国内免费 | 9019篇 |
专业分类
耳鼻咽喉 | 32050篇 |
儿科学 | 68904篇 |
妇产科学 | 61477篇 |
基础医学 | 311873篇 |
口腔科学 | 64386篇 |
临床医学 | 197394篇 |
内科学 | 420541篇 |
皮肤病学 | 49527篇 |
神经病学 | 172292篇 |
特种医学 | 86926篇 |
外国民族医学 | 627篇 |
外科学 | 334309篇 |
综合类 | 61239篇 |
现状与发展 | 21篇 |
一般理论 | 689篇 |
预防医学 | 158104篇 |
眼科学 | 53405篇 |
药学 | 173782篇 |
89篇 | |
中国医学 | 9339篇 |
肿瘤学 | 127837篇 |
出版年
2018年 | 23404篇 |
2017年 | 18956篇 |
2016年 | 20826篇 |
2015年 | 24169篇 |
2014年 | 32984篇 |
2013年 | 47009篇 |
2012年 | 63436篇 |
2011年 | 67184篇 |
2010年 | 40105篇 |
2009年 | 37553篇 |
2008年 | 61682篇 |
2007年 | 66290篇 |
2006年 | 66743篇 |
2005年 | 64138篇 |
2004年 | 61141篇 |
2003年 | 58733篇 |
2002年 | 57141篇 |
2001年 | 105906篇 |
2000年 | 108823篇 |
1999年 | 91929篇 |
1998年 | 25238篇 |
1997年 | 22808篇 |
1996年 | 22078篇 |
1995年 | 20774篇 |
1994年 | 19181篇 |
1993年 | 17807篇 |
1992年 | 69944篇 |
1991年 | 67548篇 |
1990年 | 66330篇 |
1989年 | 64335篇 |
1988年 | 59285篇 |
1987年 | 58144篇 |
1986年 | 55369篇 |
1985年 | 52464篇 |
1984年 | 38987篇 |
1983年 | 33112篇 |
1982年 | 19337篇 |
1979年 | 36721篇 |
1978年 | 25795篇 |
1977年 | 22637篇 |
1976年 | 20330篇 |
1975年 | 23073篇 |
1974年 | 27245篇 |
1973年 | 26573篇 |
1972年 | 25296篇 |
1971年 | 23684篇 |
1970年 | 22204篇 |
1969年 | 21359篇 |
1968年 | 19698篇 |
1967年 | 17652篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
Rapid adenosine release in the nucleus tractus solitarii during defence response in rats: real-time measurement in vivo 总被引:6,自引:3,他引:3
Nicholas Dale Alexander V. Gourine Enrique Llaudet David Bulmer Teresa Thomas† K. Michael Spyer 《The Journal of physiology》2002,544(1):149-160
We have measured the release of adenosine and inosine from the dorsal surface of the brainstem and from within the nucleus tractus solitarii (NTS) during the defence response evoked by hypothalamic stimulation in the anaesthetised rat. At the surface of the brainstem, only release of inosine was detected on hypothalamic defence area stimulation. This inosine signal was greatly reduced by addition of the ecto-5'-nucleotidase inhibitor α,β-methylene ADP (200 μM), suggesting that the inosine arose from adenosine that was produced in the extracellular space by the prior release of ATP. By placing a microelectrode biosensor into the NTS under stereotaxic control we have recorded release of adenosine within this nucleus. By contrast to the brainstem surface, a fast increase in adenosine, accompanied only by a much smaller change in inosine levels, was seen following stimulation of the hypothalamic defence area. The release of adenosine following hypothalamic stimulation was mainly confined to a narrow region of the NTS some 500 μm in length around the level of the obex. Interestingly the release of adenosine was depletable: when the defence reaction was evoked at short time intervals, much less adenosine was released on the second stimulus. Our novel techniques have given unprecedented real-time measurement and localisation of adenosine release in vivo and demonstrate that adenosine is released at the right time and in sufficient quantities to contribute to the cardiovascular components of the defence reaction. 相似文献
993.
994.
995.
Previously, we prepared two different monoclonal antibodies (mAbs) against human 4-1BB (CD137): an agonistic mAb BBK-1 and an antagonistic mAb BBK-2. In this paper, we describe the molecular cloning of these two mAbs and present comparisons of their amino acid sequences. cDNAs encoding the heavy (H) and light (L) chains of the two mAbs were cloned by screening of cDNA libraries constructed from hybridomas secreting these mAbs. Comparisons of amino acid sequences of the two mAbs showed that, while the constant regions of the H and L chains were identical between the two mAbs, the variable region showed 45% identity in H chains and 48% identity in L chains. This suggests that these two mAbs recognize different epitopes of 4-1BB and may have different effects on the activity of 4-1BB. 相似文献
996.
997.
998.
Prevention of Bone Loss by Clodronate in Early Postmenopausal Women with Vertebral Osteopenia: A Dose-Finding Study 总被引:1,自引:0,他引:1
M. J. V?lim?ki K. Laitinen K. Laitinen A. Patronen H. Puolijoki H. Puolijoki J. Sepp?nen L. Pylkk?nenand the Probone Study Group 《Osteoporosis international》2002,13(12):937-947
This double-masked, placebo-controlled study was undertaken to determine the efficacy and safety of oral clodronate in the
prevention of bone loss in early postmenopausal women with vertebral osteopenia. Altogether 610 women with a mean age of 53
years were recruited for the study. They were 1–5 years postmenopausal and their lumbar spine bone mineral density (BMD) was
at least 1 standard deviation below the mean of premenopausal women (T-score ≤−1). The subjects were randomized into five study groups to receive either placebo, clodronate 65 mg, 400 mg or 800
mg daily, or intermittent clodronate in 3 month cycles with 400 mg daily for 15 days followed with no treatment for 75 days
for 3 years. One hundred and eighty-seven of 509 women who completed the primary study continued in the extension study of
2 years in which previous placebo users were switched to clodronate 800 mg daily, while previous users of 400 mg or 800 mg
of clodronate used either placebo or 800 mg of clodronate daily. In the primary study clodronate was administered in the evening,
and in the extension 1 h before breakfast on an empty stomach. In the primary study mean changes in lumbar spine BMD were
−3.4% in the placebo group and +0.4% in 800 mg clodronate group [difference between groups at 3 years 3.8% (95% CI 2.7% to
4.9%, p<0.0001)], and in the trochanter area BMD −1.1% in the placebo group, and + 0.4% in the 800 mg clodronate group [difference
between groups at 3 years 1.5% (95% CI 0.05% to 2.9%)]. During the extension study mean changes in lumbar spine BMD were +1.5%
in the clodronate group and −0.2 % in the placebo group [difference between groups 1.7% (CI 0.4% to 3.0%, p = 0.010)] and in trochanter BMD were +2.5% in the clodronate group and no change in the placebo group [difference between
groups 2.1% (CI 0.3% to 3.9%, p = 0.007)]. No statistically significant differences between the placebo and 800 mg clodronate groups were found in the femoral
neck BMD. In the primary study the urinary excretion of type I collagen aminoterminal telopeptide (NTX) decreased by 44% (p<0.0001 compared with placebo) and that of deoxypyridinoline by 18% (p<0.0001) in the clodronate 800 mg group. In the extension study urinary NTX decreased by 51% (p<0.0001) in those who were switched to 800 mg of clodronate and increased by 67% (p<0.0001) in those who stopped using that dose. There was no difference in the frequency of gastrointestinal complaints between
clodronate- and placebo-treated patients in the primary study, but they were more common among women who received clodronate
in the extension phase. Clodronate in daily doses of 400–800 mg caused a slight elevation of aminotransferase levels, usually
within the reference range. In bone biopsies no defect in mineralization was found. In conclusion, clodronate in a daily dose
of 800 mg prevents early postmenopausal bone loss at the sites of the skeleton in which cancellous bone predominates. It effectively
reduces bone resorption and bone turnover rate. Antifracture efficacy of clodronate remains to be established by prospective,
placebo-controlled trials.
Received: 4 March 2002 / Accepted: 9 July 2002 相似文献
999.
J M Ragnaud H Gin P Tauzin-Fin P Ballanger R Ballanger J Aubertin 《Pathologie-biologie》1983,31(5):434-437
The main point of this study resides in comparing the efficiency and the disadvantages of using cefazoline and cotrimoxazole in the prevention of post-surgery infections of the low urinary tract. 91 patients who were about to undergo urologic surgery were divided in three groups for randomisation. 31 patients received 500 mg of intramuscular cefazoline every eight hours, the day before surgery, the day of surgery and five days following surgery. 30 others received 800 mg of intramuscular sulfametoxazole and 160 mg of trimetoprime every 12 hours during the same lapse of time. The third group of 30 patients did not receive any antibiotics. Age, sex, clinical pathology needing surgery and indwelling catheter were the same in the three groups. The group treated by cefazoline, presented 5 post surgery infections among which 3 transitory fevers and 2 isolated bacteriurias. In the group treated by cotrimoxazole, there were 7 post surgery infections among which 3 fevers and 4 isolated bacteriurias. Tolerance in both cases was similar. In the control group, there were 19 post-surgery infections with 2 cases of sepsis, 14 transitory fevers and 3 isolated bacteriurias. These results show the importance of antibiotic prophylaxy in urologic surgery of the low genital tract whether the patient has a urethral catheter or not and whatever the type of urologic surgery. But, there is no significant difference between cefazoline and cotrimoxazole. 相似文献
1000.
Abra R. M. Hunt C. Anthony Fu K. K. Peters J. H. 《Cancer chemotherapy and pharmacology》1983,11(2):98-101
Cancer Chemotherapy and Pharmacology - Addition of solid doxorubicin or solutions to pre-formed liposomes proved to be the optimal method for incorporating the drug into liposomes whilst... 相似文献