全文获取类型
收费全文 | 22446篇 |
免费 | 1852篇 |
国内免费 | 623篇 |
专业分类
耳鼻咽喉 | 105篇 |
儿科学 | 320篇 |
妇产科学 | 193篇 |
基础医学 | 1610篇 |
口腔科学 | 167篇 |
临床医学 | 1930篇 |
内科学 | 5172篇 |
皮肤病学 | 313篇 |
神经病学 | 1149篇 |
特种医学 | 583篇 |
外国民族医学 | 1篇 |
外科学 | 2478篇 |
综合类 | 1668篇 |
现状与发展 | 2篇 |
预防医学 | 659篇 |
眼科学 | 242篇 |
药学 | 5404篇 |
10篇 | |
中国医学 | 317篇 |
肿瘤学 | 2598篇 |
出版年
2024年 | 30篇 |
2023年 | 518篇 |
2022年 | 625篇 |
2021年 | 1099篇 |
2020年 | 1041篇 |
2019年 | 941篇 |
2018年 | 841篇 |
2017年 | 940篇 |
2016年 | 857篇 |
2015年 | 959篇 |
2014年 | 1291篇 |
2013年 | 2519篇 |
2012年 | 1170篇 |
2011年 | 1337篇 |
2010年 | 1018篇 |
2009年 | 1026篇 |
2008年 | 998篇 |
2007年 | 949篇 |
2006年 | 877篇 |
2005年 | 713篇 |
2004年 | 572篇 |
2003年 | 563篇 |
2002年 | 508篇 |
2001年 | 394篇 |
2000年 | 330篇 |
1999年 | 278篇 |
1998年 | 272篇 |
1997年 | 260篇 |
1996年 | 209篇 |
1995年 | 198篇 |
1994年 | 162篇 |
1993年 | 159篇 |
1992年 | 120篇 |
1991年 | 108篇 |
1990年 | 100篇 |
1989年 | 92篇 |
1988年 | 77篇 |
1987年 | 94篇 |
1986年 | 64篇 |
1985年 | 85篇 |
1984年 | 81篇 |
1983年 | 57篇 |
1982年 | 80篇 |
1981年 | 57篇 |
1980年 | 57篇 |
1979年 | 45篇 |
1978年 | 44篇 |
1977年 | 28篇 |
1976年 | 28篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Previously we found that inhibitors of noradrenaline (NA) and/or 5-HT reuptake are able to inhibit neuronal nicotinic acetylcholine receptors (nAChRs) in the CNS most probably by a channel blocker-type mechanism. The aim of our study was to clarify whether selective dopamine uptake inhibitors also possess this property, therefore we investigated the effect of GBR-12909 on the nicotine-evoked release of [3H]NA from rat hippocampal slices. GBR-12909, similar to selective NA and 5-HT uptake blockers, inhibited the nicotine-evoked release with an IC50 of 2.32 microM. The ability of monoamine uptake blockers to inhibit nicotine-evoked [3H]NA release (IC50) and NA reuptake (Ki) showed no correlation, indicating that the NA uptake system is not involved in the inhibition of the response to nicotine. Previously we have shown in whole cell patch clamp experiments, that GBR-12909, depending on the stimulation pattern, inhibits Na+-currents with an IC50 in the 6-35 microM concentration range [Mike A, Karoly R, Vizi ES, Kiss JP (2003) Inhibitory effect of the DA uptake blocker GBR-12909 on sodium channels of hippocampal neurons. Neuroreport 14:1945-1949]. To study whether the inhibition of Na+-channels is involved in the action of GBR-12909 on the nicotine-evoked [(3)H]NA release, we compared the effect of GBR-12909 and the Na(+)-channel blocker tetrodotoxin (TTX) on the electrical stimulation- and nicotine-evoked response. TTX prevented the release of [3H]NA induced by both types of stimulation, whereas GBR-12909 inhibited only the nicotine-induced response, indicating that under our experimental conditions the target of GBR-12909 is not the Na+-channel. These data indicate that the selective DA uptake inhibitor GBR-12909 is able to inhibit nAChRs, that is, the nAChR antagonistic property of monoamine uptake inhibitors is independent of their selectivity. The fact that monoamine uptake inhibitors with different chemical structure and selectivity are able to inhibit nAChRs may reveal some common properties of nicotinic receptors and monoamine uptake carriers. 相似文献
992.
In the months following transection of adult rat peripheral nerve some sensory neurons undergo apoptosis. Two weeks after sciatic nerve transection some neurons in the L4 and L5 dorsal root ganglia begin to show immunoreactivity for nestin, a filament protein expressed by neuronal precursors and immature neurons, which is stimulated by neurotrophin-3 (NT-3) administration. The aim of this study was to examine whether NT-3 administration could be compensating for decreased production of neurotrophins or their receptors after axotomy, and to determine the effect on nestin synthesis. The levels of mRNA in the ipsilateral and contralateral L4 and L5 dorsal root ganglia were analyzed using real-time polymerase chain reaction, 1 day, 1, 2 and 4 weeks after unilateral sciatic nerve transection and NT-3 or vehicle administration via s.c. micro-osmotic pumps. In situ hybridization was used to identify which cells and neurons expressed mRNAs of interest, and the expression of full-length trkC and p75NTR protein was investigated using immunohistochemistry. Systemic NT-3 treatment increased the expression of brain-derived neurotrophic factor, nestin, trkA, trkB and trkC mRNA in ipsilateral ganglia compared with vehicle-treated animals. Some satellite cells surrounding neurons expressed trkA and trkC mRNA and trkC immunoreactivity. NT-3 administration did not affect neurotrophin mRNA levels in the contralateral ganglia, but decreased the expression of trkA mRNA and increased the expression of trkB mRNA and p75NTR mRNA and protein. These data suggest that systemically administered NT-3 may counteract the decrease, or even increase, neurotrophin responsiveness in both ipsi- and contralateral ganglia after nerve injury. 相似文献
993.
Anuradha K Sailaja VV Umabala P Satheesh T Lakshmi V 《Indian journal of medical microbiology》2007,25(3):203-208
PURPOSE: To evaluate the spectrum of activity of three beta-lactamase inhibitors such as amoxicillin/ clavulanic acid, ticarcillin/ clavulanic acid and piperacillin/ tazobactam in comparison to cephalosporins against gram negative bacilli. METHODS: Gram-negative bacilli isolated from the clinical specimens received in the laboratory were included in the study. Using the API system (bioMiotarieux) during a one-year period, a total of 1,252 Enterobacteriaceae and 385 non-fermenters were evaluated. RESULTS: The percentage resistance of the Enterobacteriaceae isolates was 82.92% to amoxicillin/ clavulanic acid, 58.22% to ticarcillin/clavulanic acid and 22.44% to piperacillin/tazobactam respectively. Pseudomonas aeruginosa showed resistance of 96% to ticarcillin/ clavulanic acid and 61% to piperacillin/ tazobactam and Acinetobacter baumannii showed 49% resistance to ticarcillin/ clavulanic acid and 77% resistance to piperacillin/ tazobactam respectively. The isolates exhibited high resistance to all the generations of cephalosporins and the other groups of antibiotics except carbapenems. CONCLUSIONS: Piperacillin/tazobactam was found to be the most active combination of the three against Enterobacteriaceae and Pseudomonas spp. and ticarcillin/clavulanic acid against Acinetobacter spp. and Stenotrophomonas maltophilia. 相似文献
994.
Lankin VZ Ivanova MV Konovalova GG Tikhaze AK Kaminnyi AI Kukharchuk VV 《Bulletin of experimental biology and medicine》2007,143(4):414-417
We studied the effects of two inhibitors of β-hydroxy-β-methylglutaryl coenzyme A reductase, simvastatin and lovastatin, on
the lag phase of ascorbate-dependent lipid oxidation in rat liver. Oxidizability of liver biological membranes significantly
increased in intact animals and rats with induced hypercholesterolemia after peroral administration of these statins. The
lag phase of ascorbate-dependent lipid oxidation in liver biomembranes decreased by 2.1 times in hypercholesterolemic rats.
In animals of the lovastatin group this parameter decreased by 4.4 times compared to the control. In intact rats receiving
simvastatin, the lag phase of oxidation in biomembranes from the liver decreased practically by 2 times. At the same time,
in animals receiving simvastatin in combination with antioxidant vitamins (vitamins E and C, provitamin A) and selenium, the
period of induction of oxidation increased by 3.3 times. Our results indicate that β-hydroxy-β-methylglutaryl coenzyme A reductase
inhibitors produce a prooxidant effect on the liver, which can be prevented by administration of antioxidant agents.
__________
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 4, pp. 390–393, April, 2007 相似文献
995.
Lakomkin VL Kapel'ko VI Lankin VZ Konovalova GG Kaminnyi AI 《Bulletin of experimental biology and medicine》2007,143(4):408-410
Long-term administration of β-hydroxy-β-methylglutaryl coenzyme A reductase inhibitor atorvastatin to rats was accompanied
by an increase in the relative weight of the heart and decrease in the rate of pressure development in the isovolumic heart.
During oxidative stress induced by addition of 100 μM H2O2 to the perfusate, the decrease in contractile function was more pronounced that in the control. Our results indicate that
administration of atorvastatin is accompanied by a decrease in myocardial contractility, which becomes more pronounced under
conditions of oxidative stress.
__________
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 4, pp. 383–385, April, 2007 相似文献
996.
The apical conjugate efflux pump ABCC2 (MRP2) 总被引:7,自引:0,他引:7
997.
Javariya Aamir Syed Mustafa Ali Maged N. Kamel Boulos Naveed Anjum Muhammad Ishaq 《Health Policy and Technology》2018,7(1):88-97
Objective
The objective of this review is to identify enabling and inhibiting factors for mHealth adoption in low resource settings, by giving emphasis on the stakeholders representing the caregiving side. Another objective of this study is to support implementation agencies (governmental and non-governmental) in designing scalable mHealth interventions.Methods
A PEO (Population, Exposure, Outcome) approach was used to formulate the review question. A pre-defined search strategy was implemented; Google Scholar, PubMed and gray literature were searched using alternate terms for “mHealth”, “adoption” and “developing countries”. CASP [7] tools were used to assess the quality of selected evidence. After applying inclusion and exclusion criteria on search results and critical appraisal of the selected evidence, twelve studies were selected for the review.Results
Adoption factors operated at the levels of organization, facility-based service provider and frontline health worker. Engagement of end users during design phase, informed clinical decision making, utilization of mHealth evidence, employers’ tolerance of some personal use of devices, automation of tasks and user-friendliness of application are key enabling factors for mHealth adoption in developing countries. On the contrary, absence of national policy on mHealth, poor knowledge base on mHealth, using two systems in parallel, duplication of efforts, poor Internet connectivity and shortage of electricity are important inhibiting factors for mHealth adoption.Conclusions
The review provides an insight about the challenges and opportunities related to mHealth adoption in developing countries. Implementation agencies should give careful consideration to these factors before designing and deploying any mHealth-enabled intervention. It is also important to understand the concept of incremental innovation so that resources spent on pilot interventions are optimized and full potential is achieved. 相似文献998.
Lizhen Cheng Ting Li Ling Dong Xiaoyu Wang Qiye Huo Haoyu Wang Zhujun Jiang Xinyu Shan Weisan Pan Xinggang Yang 《Journal of pharmaceutical sciences》2018,107(5):1434-1442
In this study, a bilayer osmotic pump tablet of flurbiprofen (FP) solid dispersions (SDs) was developed to increase the solubility of the poorly soluble drug and controlled drug release at a constant rate. Based on the investigation of thermodynamic properties the drug, the carrier, and the calculation of the solubility parameters, the FP-SD was prepared by hot-melt extrusion technique with the povidone (PVP) VA64 carrier. Then, central composite design-response surface methodology was used to evaluate the influence of factors on the responses. Consequently, PVP VA64 was selected as the carrier for preparing FP-SD. The results of differential scanning calorimetry and X-ray confirmed that FP in FP-SD was in an amorphous state. FTIR indicated that the intermolecular hydrogen bond probably formed between FP and PVP VA64 in FP-SD. Correlation of release profiles to zero-order kinetics was significant (R2 = 0.9939). The mathematical models had good predictability because the deviation was less than 1% between the predicted value and measured value. These results demonstrated that FP-SD osmotic pump tablets successfully increased the solubility of FP and controlled the release of FP at a constant rate. 相似文献
999.
1000.
Kasirawat Sawangrat Masaki Morishita Kosuke Kusamori Hidemasa Katsumi Toshiyasu Sakane Akira Yamamoto 《Journal of pharmaceutical sciences》2018,107(11):2946-2956
Breast cancer resistance protein (BCRP) transporter is an efflux transporter that utilizes energy from adenosine triphosphate hydrolysis to push its substrates, regardless of the concentration gradient. Its presence on the apical membrane of the intestinal mucosa is a major obstacle for the intestinal absorption of its substrates. In this study, we examined the effects of various pharmaceutical excipients on the intestinal transport and absorption of sulfasalazine, a BCRP substrate. Four excipients, including 0.05% and 0.075% BL-9EX, 0.01% and 0.05% Brij 97, 0.075% Labrasol, and 0.05% and 0.1% Tween 20 decreased the secretory transport of sulfasalazine in an in vitro diffusion chamber. Further investigation in an in situ closed loop experiment in rats showed that 0.05% and 0.1% BL-9EX and 0.1% Brij 97 effectively enhanced the intestinal absorption of sulfasalazine while maintaining minimal toxicity to the intestinal mucosa. However, 0.1% Brij 97 also increased the intestinal absorption of 5(6)-carboxyfluorescein, a paracellular marker compound. These findings suggest that BL-9EX might effectively inhibit the BCRP-mediated efflux of sulfasalazine in vivo, indicating that BL-9EX could improve the intestinal absorption of sulfasalazine and other BCRP substrates. 相似文献