全文获取类型
收费全文 | 6692篇 |
免费 | 387篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 94篇 |
妇产科学 | 69篇 |
基础医学 | 1038篇 |
口腔科学 | 148篇 |
临床医学 | 501篇 |
内科学 | 1524篇 |
皮肤病学 | 80篇 |
神经病学 | 793篇 |
特种医学 | 215篇 |
外科学 | 1084篇 |
综合类 | 28篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 357篇 |
眼科学 | 191篇 |
药学 | 483篇 |
中国医学 | 12篇 |
肿瘤学 | 488篇 |
出版年
2024年 | 7篇 |
2023年 | 53篇 |
2022年 | 185篇 |
2021年 | 307篇 |
2020年 | 131篇 |
2019年 | 199篇 |
2018年 | 202篇 |
2017年 | 123篇 |
2016年 | 173篇 |
2015年 | 209篇 |
2014年 | 294篇 |
2013年 | 328篇 |
2012年 | 564篇 |
2011年 | 567篇 |
2010年 | 311篇 |
2009年 | 271篇 |
2008年 | 471篇 |
2007年 | 461篇 |
2006年 | 424篇 |
2005年 | 405篇 |
2004年 | 396篇 |
2003年 | 330篇 |
2002年 | 301篇 |
2001年 | 31篇 |
2000年 | 14篇 |
1999年 | 33篇 |
1998年 | 41篇 |
1997年 | 55篇 |
1996年 | 27篇 |
1995年 | 28篇 |
1994年 | 15篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1964年 | 4篇 |
1961年 | 7篇 |
1960年 | 5篇 |
排序方式: 共有7137条查询结果,搜索用时 15 毫秒
21.
A new type of continuous, supermacroporous, monolithic, cryogel affinity adsorbent was developed, allowing specific fractionation and separation of human peripheral blood lymphocytes in a chromatographic format. The affinity adsorbent was used to design a novel cell separation strategy, which was based on the interaction of protein A from Staphylococcus aureus with cells bearing IgG antibodies on the surface. After treating lymphocytes with goat anti-human IgG(H+L), the IgG-positive B-lymphocytes were efficiently separated from T-lymphocytes. Protein A covalently coupled to epoxy activated dimethylacrylamide (DMAA) cryogel matrix specifically bound IgG-bearing B-lymphocytes through the Fc region, while non-bound T-lymphocytes passed through the column. More than 90% of the B-lymphocytes were retained in the column while the cells in the breakthrough fraction were enriched in T-lymphocytes (81%). The viability of the T-lymphocytes isolated was greater than 90%. The bound lymphocytes released by human or dog IgG recovered 60-70% of the B-cells without significantly impairing the cell viability. The technique can be applied in general to cell separation systems where IgG antibodies against specific cell surface markers are available. 相似文献
22.
Schindler I Rice NJ McIntosh RD Rossetti Y Vighetto A Milner AD 《Nature neuroscience》2004,7(7):779-784
When we reach out to pick something up, our arm is directed to the target by visuomotor networks in the cortical dorsal stream. However, our reach trajectories are influenced also by nontarget objects, which might be construed as potential obstacles. We tested two patients with bilateral dorsal-stream (parietal lesions, both of whom were impaired at pointing to visual stimuli (optic ataxia). We asked them to reach between two cylinders, which varied in location from trial to trial. We found that the patients' reaches remained invariant with changes in obstacle location. In a control task when they were asked to point midway between the two objects, however, their responses shifted in an orderly fashion. We conclude that the dorsal stream provides the visual guidance we automatically build into our movements to avoid potential obstacles, as well as that required to ensure arrival at the target. 相似文献
23.
Jacques Chappuis Igor A. Sherman A. Wilhelm Neumann 《Annals of biomedical engineering》1983,11(5):435-449
Measurements of the surface tension of articular cartilage and friction experiments were carried out to provide further evidence
in support of a new theory regarding the mechanism of friction in joints. To determine the surface tension of cartilage, contact
angle measurements were used in conjunction with the equation of state for interfacial tensions. The advancing contact angle
between saline drops and articular cartilage was found to be 100°±5°, indicating a highly hydrophobic surface. The corresponding
surface tension value was calculated to be 22.5 ergs/cm2. Friction of cartilage against hydrophobic surfaces is shown to be lower than the friction of cartilage against hydrophilic
surfaces. All these results further support the theory that lubrication by nonwetting drops occurs in joints and may be responsible
for the exceptional friction characteristics of the joints. 相似文献
24.
Igor Babaryka 《Virchows Archiv : an international journal of pathology》1978,377(2):181-187
Summary A polypoid tumor was surgically removed from the second part of the duodenum of a 56-year-old male. The main body consisted of large epithelioid cells arranged in an adenoma like pattern of strands and nests. These cells were argyrophil and had marked nonspecific esterase activity. Unmyelinated nerves with proliferated Schwann cells accompanied these epithelioid cells together with scattered gangliocyte like elements. Ultramicroscopically, the epithelioid cells were seen to contain round electron dense granules, 150 nm in diameter on average. The tumor is considered to be a nonchromaffin paraganglioma, as it probably developed from paraganglion cells associated with small arteries or branches of the vagus nerve, or from the undifferentiated pluripotent APUD cells of the duodenum. 相似文献
25.
26.
27.
Sergey V. Lindeman Igor I. Ponomaryov Nikolai I. Raevsky Yurii T. Struchkov Alexandr L. Rusanov 《Macromolecular chemistry and physics.》1994,195(2):555-570
The X-ray structural investigation of the naphthoylenebis-(benzimidazole) ( 1 ) cis- and trans-isomers as models for the cis and trans elementary units of the corresponding poly(naphthoylene-benzimidazoles) (PNBI) was carried out. The correctness of the previous identification of the isomers was confirmed, and exact geometrical parameters of the PNBI elementary units (required, in particular, for the calculation of the Kuhn segment of PNBI) were determined. Quantum-chemical semi-empirical calculations of the ground and excited electronic states of the isomers were carried out. Both experimental and theoretical data confirm a larger stability of the planar π-conjugated structure of the trans-isomer in comparison with the cis-isomer in the ground as well as in the excited electronic state. Crystals of the cis- and trans-isomers obtained from trifluoroacetic acid solutions are the solvates of bis(trifluoroacetates) of diprotonated 1 with an extremely high content of the solvating trifluoroacetic acid. This peculiarity is favourable for modelling the main characteristics of the interaction between PNBI and protonic polar solvent molecules, viz. preferred types of H-bonding and a possibility of interaction of the electronic lone pairs of the solvent molecules with the π-electronic systems of the elementary units of PNBI by charge transfer complexes. 相似文献
28.
29.
30.
Timothy D. Lyon Igor Frank Matthew K. Tollefson Robert F. Tarrell Paras H. Shah Robert H. Thompson Robert J. Karnes Stephen A. Boorjian 《Urologic oncology》2021,39(6):370.e1-370.e8
IntroductionIntraoperative hypothermia (IOH) has been suggested to adversely impact outcomes following surgery. The objective of this study was to evaluate the association between IOH and survival following radical cystectomy (RC).MethodsPatients who underwent RC for bladder cancer from 2003 to 2018 were identified in our cystectomy registry. Intraoperative temperatures were extracted from the anesthesia record. IOH was defined as a median intraoperative temperature <36°C, and severe IOH as ≤ 35°C. Time under 36°C was assessed as a continuous variable. Recurrence-free survival (RFS), cancer-specific survival (CSS), and overall survival (OS) were estimated using the Kaplan-Meier method. Associations between IOH and outcomes were assessed with multivariable Cox proportional hazards models.ResultsA total of 852 patients were identified, among whom 274 (32%) had IOH. Median follow up among survivors was 4.9 years (IQR 2.4–8.7), during which time 483 patients died, including 343 from bladder cancer. Two-year survival was not significantly different between patients with and without IOH (CSS: 74% vs. 71%, P= 0.31; OS: 68% vs. 67%, P= 0.13). Following multivariable adjustment, neither IOH nor time under 36°C was significantly associated with survival. A total of 37 patients (4.3%) had severe IOH. These patients were observed to have significantly lower 2-year OS (56% vs. 68%, P= 0.005); however, this association did not remain statistically significant after multivariable adjustment (P= 0.92).ConclusionIOH was not independently associated with survival following RC. These data do not support IOH as a prognostic factor for cancer outcomes among patients undergoing RC. 相似文献