全文获取类型
收费全文 | 177789篇 |
免费 | 14567篇 |
国内免费 | 7576篇 |
专业分类
耳鼻咽喉 | 1111篇 |
儿科学 | 4927篇 |
妇产科学 | 3799篇 |
基础医学 | 24515篇 |
口腔科学 | 3761篇 |
临床医学 | 14400篇 |
内科学 | 27651篇 |
皮肤病学 | 2809篇 |
神经病学 | 18490篇 |
特种医学 | 2994篇 |
外国民族医学 | 47篇 |
外科学 | 13485篇 |
综合类 | 25609篇 |
现状与发展 | 25篇 |
预防医学 | 10886篇 |
眼科学 | 3723篇 |
药学 | 22590篇 |
40篇 | |
中国医学 | 5372篇 |
肿瘤学 | 13698篇 |
出版年
2024年 | 327篇 |
2023年 | 1996篇 |
2022年 | 4023篇 |
2021年 | 5779篇 |
2020年 | 5053篇 |
2019年 | 4775篇 |
2018年 | 4789篇 |
2017年 | 5303篇 |
2016年 | 5652篇 |
2015年 | 6037篇 |
2014年 | 10202篇 |
2013年 | 12584篇 |
2012年 | 10454篇 |
2011年 | 11801篇 |
2010年 | 9864篇 |
2009年 | 9677篇 |
2008年 | 10197篇 |
2007年 | 9988篇 |
2006年 | 8868篇 |
2005年 | 7889篇 |
2004年 | 6862篇 |
2003年 | 6125篇 |
2002年 | 5065篇 |
2001年 | 4409篇 |
2000年 | 3894篇 |
1999年 | 3338篇 |
1998年 | 3206篇 |
1997年 | 2897篇 |
1996年 | 2660篇 |
1995年 | 2287篇 |
1994年 | 1970篇 |
1993年 | 1691篇 |
1992年 | 1394篇 |
1991年 | 1214篇 |
1990年 | 1039篇 |
1989年 | 843篇 |
1988年 | 677篇 |
1987年 | 618篇 |
1986年 | 577篇 |
1985年 | 772篇 |
1984年 | 624篇 |
1983年 | 408篇 |
1982年 | 554篇 |
1981年 | 390篇 |
1980年 | 311篇 |
1979年 | 201篇 |
1978年 | 159篇 |
1977年 | 125篇 |
1976年 | 111篇 |
1975年 | 85篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
T. Shioya M. Kagaya M. Sano M. Itaba T. Shindo M. Miura 《European journal of clinical pharmacology》1996,50(5):375-380
Objective:
We studied the bronchodilatory effect of tiquizium bromide [3-(di-2-thienylmethylene)-5-methyl-trans-quinolizidinium bromide; TQZ], an antimuscarinic agent, on airway smooth muscle in vitro, and also in patients with chronic
obstructive pulmonary disease (COPD).
Methods:
In the first experiment, canine tracheal smooth muscle was used to measure the pA2 of TQZ in vitro. The selectivity of TQZ
for muscarinic receptor subtypes was also examined with a radioligand binding assay.
Results:
The pA2 value of TQZ was 8.75. The pK
i values of TQZ for M1, M2, and M3 were 8.70, 8.94, and 9.11, respectively. In an open pilot experiment, the effects of TQZ
inhalation were studied in seven patients with COPD (seven men, mean age 68.5 years). TQZ significantly increased forced vital
capacity (FVC) and forced expiratory volume in 1 s (FEV1) in a dose-dependent manner. The mean maximum increases in FVC and FEV1 caused by inhaled TQZ (2.0 mg) were 24% and 29%, respectively, and they were measured 1 h after the drug had been inhaled.
The FVC and FEV1 were still significantly higher than the control values even 8 h after the drug had been inhaled. No adverse effects were
observed after inhalation of TQZ.
Conclusion:
These data suggest that TQZ is an effective antimuscarinic agent, and that it causes significant bronchodilation in patients
with COPD.
Received: 3 April 1995/Accepted in revised form: 27 November 1995 相似文献
992.
Tohru Hashimoto M.D. Hironobu Nakamura Shinichi Hori Kaname Tomoda Katsuyuki Nakanishi Takamichi Murakami Takahiro Kozuka Morito Monden Mitsukazu Gotoh Chikazumi Kuroda Kenichi Wakasa Masami Sakurai 《Cardiovascular and interventional radiology》1995,18(2):82-86
Purpose: To evaluate the efficacy of transcatheter oily chemoembolization (TOCE) for hepatoceliular carcinoma (HCC) on the basis
of microscopic and macroscopic findings postembolization.
Methods: HCCs ranging in size from 0.5 to 13 cm (mean 3.6 cm) were obtained from partial hepatectomies of 100 consecutive patients
who had undergone TOCE between 20 and 246 days (mean 59.5 days) prior to surgery. The efficacy of TOCE was assessed on the
basis of the necrotic to live cell ratio of the tumors. The microscopic pattern of tumor growth was grouped into expanding
type (complete capsule formation) and replacing type (incomplete or no capsule). There were five types of macroscopic groupings:
single nodule, single nodule with extranodular growth (SNE), contiguous and noncontiguous multinodular, and massive growth
type.
Results: Among 79 cases with the expanding type, 29 (37%) had 100% HCC necrosis, but none with 100% necrosis were in the replacing
type. By macroscopic grouping, the efficacy of TOCE decreased from the single nodule type (50% of patients had 100% necrosis)
to the SNE type (21%), and the other types (9%). 相似文献
993.
AMPA/kainate receptor activation in cultured oligodendrocyte precursor cells from embryonic mouse cortex leads to a blockade of delayed rectifying K+ currents. In the present study, we provide evidence using the patch-clamp technique in the whole-cell configuration that the mechanism linking kainate receptor activation and K+ conductance blockade is due to the receptor-mediated Na+ entry: (1) The blockade was not observed in Na+ -free bathing solution nor when intracellular [Na+] was elevated by dialzying the cell with a pipette solution containing high [Na+]. (2) Elevation of intracellular [Na+] alone led to a blockade of outward currents in contrast to cells dialyzed by sucrose. High [Li+]i also reduced the outward currents, and in Li+-containing bathing solution the kainate-induced blockade of K+ channels was more pronounced. Probably, Li+ accumulates intracellularly after permeation through the receptor pore due to slower extrusion mechanisms. Experiments with GTPγS or GDPβS and pertussis toxin indicated that GTP-binding protein-mediated mechanisms were not of importance for the kainate-induced K+ conductance blockade. Our data suggest that in glial precursor cells AMPA/kainate receptor activation leads to an intracellular [Na+] increase which blocks delayed rectifying K+ channels. © 1995 Wiley-Liss, Inc. 相似文献
994.
995.
Photic evoked responses were recorded from the striate cortex of Long-Evans hooded intact, monocular visual deprivation (MD) and MD treated with NGF rats. The averaged visual evoked responses (AVER) were obtained from both hemispheres and provided comparison after binocular photic stimuli between the contralateral and the ipsilateral striate cortex with relation to the MD eye. One month of monocular visual deprivation at the critical period of development resulted in marked reduction of the amplitudes of AVER components as compared to the control recordings (P < 0.001). These changes of the AVER could be prevented by NGF infusion to lateral ventricle at the dosage of 2.0–2.4 μg/day for four weeks during the monocular deprivation. In conclusion, the change of AVER amplitudes induced by monocular visual deprivation during the critical period of development can be prevented by NGF infusion to lateral ventricle. 相似文献
996.
J. G. WHITE † S. BURRIS† C. M. SMITH II† 《European journal of clinical investigation》1995,25(4):241-249
Abstract. The present study has evaluated the influence of high concentrations of cytochalasins B and E on the detergent-resistant actin levels in fully spread platelets by PAGE gel electrophoresis, and the effects of the two inhibitors of new actin filament assembly on translocation of fibrinogen gold (Fgn/Au) labelled GPIIb-IIIa receptors on the surface-activated cells. Concentrations of 10- 4 m and 10-5 m cytochalasin B and E reduced detergent-resistant actin in fully spread platelets to levels present in resting discoid platelets in suspension. Despite reduction of actin filaments to levels in resting cells, cytochalasin B did not prevent translocation of Fgn/Au from platelet margins into channels of the open canalicular system (OCS). Similar concentrations of cytochalasin E completely blocked translocation of receptor-ligand complexes and produced a patching phenomenon not observed in previous studies. Rinsing of the spread cells to remove cytochalasin, followed by incubation of the treated platelets in Hank's buffered salt solution (HBSS) restored levels of detergent-resistant actin to those found in untreated, spread platelets. Resting grids of 10 5 m cytochalasin E-treated platelets on drops of HBSS for 15min restored their ability to clear FGN/Au linked to GPIIb-IIIa from exposed surfaces to the OCS, but 10-4 m cytochalasin E-treated cells remained anergic after incubation on drops of HBSS. Thus a fully assembled cytoplasmic actin filament cytoskeleton does not appear to be essential for translocating receptor-ligand complexes on the platelet surface to the OCS, nor does its presence guarantee that the ability to clear GPIIb-IIIa receptors will be restored. 相似文献
997.
鼠脾细胞肿瘤坏死因子的诱生和检测 总被引:6,自引:1,他引:5
本文报道采用E.coli LPS刺激ALB/C小鼠脾细胞诱生TNF的最适条件,并用人TNF ELISA方法检测小鼠TNF。结果显示:脾细胞经LPS刺激2h就可在上清液中测出TNF,12h达高峰,LPS最适刺激浓度为10^-2μg/ml,TNF产量依赖于脾细胞的浓度。 相似文献
998.
This review examines the evidence that a subset of patients with breast cancer have tumors that are stimulated to grow by host cells in the tumor stroma. The search for such a minority group was prompted by the following observations. Adjuvant chemotherapy which is immunosuppressive improves disease-free interval and survival, whereas non-specific immunostimulation worsens the prognosis. Intrinsic immune reactivity is associated with a poor prognosis. A subset of tumors with a bad prognosis has anaplastic cells, dermal lymphatic invasion and a moderate to intense lymphoplasmacytic stromal infiltrate. Evidence is reviewed that adjuvant chemotherapy may be beneficial by virtue of its immunosuppressive effects in addition to tumor kill of minimal residual disease. 相似文献
999.
1000.
Granulocyte-macrophage colony stimulating factor (GM-CSF) modulates various functions of monocytes/ macrophages including antigen-presenting capacity. Recently it was found that astrocytes produce GM-CSF in the central nervous system (CNS) and that GM-CSF can induce proliferation and morphological changes of microglia. Here we show that GM-CSF can down regulate the interferon-γ-mediated induction of major histocompatibility complex (MHC) class II antigens in microglia, but not in astrocytes. GM-CSF pretreatment completely prevents myelin basic protein-specific T cell proliferation induced by microglia but not astrocytes. GM-CSF did not affect the cell surface expression on microglia of either MHC class I or cell adhesion molecules. The inhibition of microglial MHC class II expression and antigen-presenting function is specific for GM-CSF, as treatment with a different CSF (interleukin-3) did not modulate microglial phenotype or functional capacity. These data suggest that GM-CSF might be involved in the regulation of immune responses within the central nervous system. 相似文献