全文获取类型
收费全文 | 300551篇 |
免费 | 279561篇 |
国内免费 | 37211篇 |
专业分类
耳鼻咽喉 | 2976篇 |
儿科学 | 5609篇 |
妇产科学 | 3616篇 |
基础医学 | 94613篇 |
口腔科学 | 3732篇 |
临床医学 | 63694篇 |
内科学 | 105893篇 |
皮肤病学 | 5385篇 |
神经病学 | 26462篇 |
特种医学 | 10342篇 |
外国民族医学 | 2篇 |
外科学 | 49722篇 |
综合类 | 52548篇 |
现状与发展 | 1篇 |
一般理论 | 105篇 |
预防医学 | 46020篇 |
眼科学 | 20064篇 |
药学 | 61820篇 |
3篇 | |
中国医学 | 46805篇 |
肿瘤学 | 17911篇 |
出版年
2021年 | 4237篇 |
2020年 | 6552篇 |
2019年 | 14093篇 |
2018年 | 14824篇 |
2017年 | 15135篇 |
2016年 | 13818篇 |
2015年 | 13813篇 |
2014年 | 14152篇 |
2013年 | 15037篇 |
2012年 | 15757篇 |
2011年 | 17657篇 |
2010年 | 18711篇 |
2009年 | 26313篇 |
2008年 | 15601篇 |
2007年 | 12297篇 |
2006年 | 11617篇 |
2005年 | 11679篇 |
2004年 | 13468篇 |
2003年 | 12351篇 |
2002年 | 12580篇 |
2001年 | 11855篇 |
2000年 | 7355篇 |
1999年 | 12662篇 |
1998年 | 14226篇 |
1997年 | 14094篇 |
1996年 | 15064篇 |
1995年 | 15306篇 |
1994年 | 15054篇 |
1993年 | 13812篇 |
1992年 | 13154篇 |
1991年 | 12535篇 |
1990年 | 11424篇 |
1989年 | 11322篇 |
1988年 | 10846篇 |
1987年 | 10175篇 |
1986年 | 9697篇 |
1985年 | 8841篇 |
1984年 | 6951篇 |
1983年 | 6924篇 |
1982年 | 8100篇 |
1981年 | 7556篇 |
1980年 | 7262篇 |
1979年 | 6906篇 |
1978年 | 6097篇 |
1977年 | 6413篇 |
1976年 | 5991篇 |
1975年 | 5755篇 |
1974年 | 5199篇 |
1973年 | 4912篇 |
1972年 | 4869篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
In der Behandlung von Frakturen spielt die Analgesie eine wesentliche Rolle. Es stellt sich daher die Frage, ob in der Klinik h?ufig eingesetzte Analgetika wie Tramadol oder Diclofenac negative Wirkungen auf die Knochenbruchheilung haben. 相似文献
32.
33.
H. Nilsson J. Johansson K. Svanberg S. Svanberg G. Jori E. Reddi A. Segalla D. Gust A. L. Moore T. A. Moore 《British journal of cancer》1997,76(3):355-364
The biodistribution of two recently developed tumour markers, trimethylated (CP(Me)3) and trimethoxylated (CP(OMe)3) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i.v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence was induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensified CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: the second and third wavelengths represent the carotenoporphyrin (CP)-related peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-related fluorescence. In most tissue types, the fluorescence intensities decreased over time. A few exceptions were observed, notably the liver, in which the intensity remained remarkably constant over the time period investigated. 相似文献
34.
Summary— KR31080 (2-butyl-5-methyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-3H-imidazo[4,5-b] pyridine) is a potent inhibitor of angiotensin type 1 (AT1 ) receptors in rabbit aorta and human recombinant AT1 receptors. In the isolated rabbit thoracic aorta, KR31080 caused a nonparallel shift to the right of the concentration-response curves to angiotensin II (All) with decreased maximal response (pD'2 = 10.1 ± 0.1), but had no effect on the contractile response induced by norepinephrine. KR31080 inhibited specific [125 I]AII binding to rabbit aortic membranes (AT, receptors) and [125 I][Sar1 , Ile8 ]AII binding to human recombinant AT1 receptors in a concentration-dependent manner with IC50 values of 0.84 ± 0.08 nM and 1.92 ± 0.15 nM, respectively, but did not inhibit specific [125 I)AII binding to bovine cerebellum membranes (ÀT2 receptors). In the Scatchard analysis, KR31080 interacted with rabbit aortic AT1 receptors in a competitive manner, similar to losartan. These results demonstrate that KR31080 is a potent and AT1 selective angiotensin receptor antagonist which exerts a competitive antagonism in the [125 I]AII binding assay and insurmountable AT1 receptor antagonism in the functional study. 相似文献
35.
Alexandros Karabetsos MD Dr ; George Karachalios MD Dr ; Paraskevoula Bourlinou RN Nurse ; Asimina Reppa RN Nurse ; Rozeta Koutri MD Dr ; Androniki Fotiadou MD Dr 《Headache》1997,37(1):12-14
The efficacy and safety of ketoprofen and paracetamol were compared for the treatment of acute migraine in a randomized, double-blind study of 64 patients. Thirty-four patients received ketoprofen 100 mg intramuscularly, and 30 patients received paracetamol 500 mg intramuscularly. Partial or complete relief of pain and other symptoms was achieved 15 to 20 minutes after administration in the ketoprofen group and within 35 minutes in the paracetamol group. Complete relief of pain was achieved within 30 to 40 minutes after ketoprofen in 28 patients (82.5%) compared to 5 patients (17.5%) in the paracetamol group. Six of the patients treated with ketoprofen needed a second dose for complete relief of pain during the 4-hour follow-up period. Side effects were rare and minimal. Our findings suggest that ketoprofen produced statistically significant benefit in the treatment of acute migraine. 相似文献
36.
37.
Carlo Bertucci Enrico Domenici Piero Salvadori 《Journal of pharmaceutical and biomedical analysis》1990,8(8-12):843-846
The application of a circular dichroism (c.d.) detection system in HPLC using a chiral stationary phase is presented. The simultaneous measurement of the absorbance and c.d. signal allows the evaluation of the anisotropy factor (g = Δ/) and thus the determination of the enantiomeric excess (e.e.) of the eluates. When this detection system is used in preparative chiral chromatography the collection of the enantiomeric fractions can be readily optimized. 相似文献
38.
Bradykinin-induced release of PGI2 from aortic endothelial cell lines: responses mediated selectively by Ca2+ ions or a staurosporine-sensitive kinase. 下载免费PDF全文
1. Bradykinin (100 nM) triggers release of nitric oxide and prostacyclin from both AG07680A and AG04762 bovine cultured aortic endothelial cells. The exposure of these cells to bradykinin is in each case associated with a striking rise in intracellular calcium ion concentration. 2. Exposure of AG07680A cells to 250 nM ionomycin was followed also by a significant release of prostacyclin, whereas 250 nM ionomycin had no capacity to stimulate release of prostacyclin from AG04762 cells. 3. There was a similar concentration-dependent increase in intracellular calcium ion concentration on exposure of AG07680A and AG04762 cells to ionomycin. 4. Exposure of AG04762 cells for 10 min to staurosporine produced a concentration-dependent inhibition (IC50 = 107 +/- 14 nM) in bradykinin-stimulated prostacyclin release. There was no similar inhibitory effect of staurosporine in AG07680A cells. 5. Bradykinin (10 nM) triggered release of nitric oxide from both AG07680A and AG04762 cells, and the effect was not inhibited by 500 nM staurosporine. There was a similar ionomycin-dependent release of nitric oxide from both cell types. 6. These results identify a common pathway for bradykinin-dependent nitric oxide release from both AG07680A and AG04762 cells, involving increases in intracellular calcium ion concentration. In contrast, the bradykinin-dependent release of prostacyclin may involve one of two pathways (involving an increase in intracellular calcium or activation of a staurosporine-sensitive kinase), and the two pathways are selectively exploited in AG07680A and AG04762 cells, respectively. 相似文献
39.
40.
Summary Contradictory immunohistochemical data have been reported on the localization of N-acetylaspartylglutamate in the rat forebrain, using different carbodiimide fixation protocols and antibody purification methods. In one case, N-acetylaspartylglutamate immunoreactivity was observed in apparent interneurons throughout all allocortical and isocortical regions, suggesting possible colocalization with GABA. In another case, strong immunoreactivity was observed in numerous pyramidal cells in neocortex and hippocampus, suggesting colocalization with glutamate or aspartate. Reconciling these disparate findings is crucial to understanding the role of N-acetylaspartylglutamate in nervous system function. Antibodies to N-acetylaspartylglutamate and a structurally related molecule, N-acetylaspartate, were purified in stages, and their cross-reactivities with protein conjugates of N-acetylaspartylglutamate and N-acetylaspartate were monitored at each stage by solidphase immunoassay. Reduction of the cross-reactivity of the anti-N-acetylaspartylglutamate antibodies to N-acetylaspartateprotein conjugates to about 1% eliminated significant staining of most pyramidal neurons in the rat forebrain. Utilizing highly purified antibodies, the distributions of N-acetylaspartylglutamate and N-acetylaspartate were examined in several major telencephalic and diencephalic regions of the rat, and were found to be distinct. N-acetylaspartylglutamate-immunoreactivity was observed in specific neuronal populations, including many groups thought to use GABA as a neurotransmitter. Among these were the globus pallidus, ventral pallidum, entopeducular nucleus, thalamic reticular nucleus, and scattered non-pyramidal neurons in all layers of isocortex and allocortex. N-acetylaspartate-immunoreactivity was more broadly distributed than N-acetylaspartylglutamate-immunoreactivity in the rat forebrain, appearing strongest in many pyramidal neurons. Although N-acetylaspartate-immunoreactivity was found in most neurons, it exhibited a great range of intensities between different neuronal types. 相似文献