全文获取类型
收费全文 | 6429篇 |
免费 | 337篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 38篇 |
儿科学 | 130篇 |
妇产科学 | 35篇 |
基础医学 | 848篇 |
口腔科学 | 185篇 |
临床医学 | 535篇 |
内科学 | 1042篇 |
皮肤病学 | 158篇 |
神经病学 | 542篇 |
特种医学 | 267篇 |
外科学 | 856篇 |
综合类 | 21篇 |
预防医学 | 1226篇 |
眼科学 | 145篇 |
药学 | 388篇 |
中国医学 | 4篇 |
肿瘤学 | 354篇 |
出版年
2022年 | 51篇 |
2021年 | 103篇 |
2020年 | 49篇 |
2019年 | 63篇 |
2018年 | 90篇 |
2017年 | 87篇 |
2016年 | 107篇 |
2015年 | 126篇 |
2014年 | 148篇 |
2013年 | 201篇 |
2012年 | 349篇 |
2011年 | 365篇 |
2010年 | 212篇 |
2009年 | 237篇 |
2008年 | 328篇 |
2007年 | 347篇 |
2006年 | 297篇 |
2005年 | 289篇 |
2004年 | 302篇 |
2003年 | 290篇 |
2002年 | 232篇 |
2001年 | 111篇 |
2000年 | 134篇 |
1999年 | 102篇 |
1998年 | 59篇 |
1997年 | 64篇 |
1996年 | 107篇 |
1995年 | 222篇 |
1994年 | 214篇 |
1993年 | 183篇 |
1992年 | 210篇 |
1991年 | 191篇 |
1990年 | 130篇 |
1989年 | 56篇 |
1988年 | 48篇 |
1987年 | 64篇 |
1986年 | 60篇 |
1985年 | 45篇 |
1984年 | 36篇 |
1983年 | 32篇 |
1982年 | 21篇 |
1981年 | 24篇 |
1980年 | 24篇 |
1979年 | 30篇 |
1978年 | 27篇 |
1977年 | 26篇 |
1975年 | 25篇 |
1974年 | 20篇 |
1973年 | 25篇 |
1971年 | 18篇 |
排序方式: 共有6774条查询结果,搜索用时 0 毫秒
31.
Chromosome studies of a case of erythroleukemia in a 57-year-old female patient were made from bone marrow aspirates using the fluorescent primary stain/counterstain methodology. The chromosome number ranged from 42 to 110. There was a high proportion of hypotetraploid cells and a few hypertetraploid and hypooctaploid ones. Structurally normal chromosomes varied in number from cell to cell, ranging from one to seven in the polyploid cells. A number of marker chromosomes were observed, some of which occurred repeatedly in two copies per hypotetraploid cell. The chromosomes involved in aberrations were tentatively identified as #3, #5, #7, #12, #13, #15, #16, #18, #19, and #21. In the abnormal chromosome #16, which was missing a normal short arm, a new kind of heterochromatin was demonstrated by sequential staining with DA-DAPI and DAPI-AMD, suggesting de novo amplification of an A-T-rich satellite DNA sequence. 相似文献
32.
A Sprague-Dawley rat model with DS sarcoma transplanted in the thigh was used to compare transcatheter locoregional i.a. and systemic i.v. administration of 5-fluorouracil (FU) at 12 dose-rate schedules: 25, 50 and 100 mg/kg; bolus, 1, 5 and 24 h infusions. In experiment A tumor (62/67 animals) as well as liver and kidney (56/67 animals) were excised 1 h after a single bolus or 1 h infusion or at the end of 5 and 24 h infusions. (19)F-NMR spectroscopy at 11.7 T was used to quantitate FU and its metabolites in ca. 1 g of tissue at 4 degrees C. In experiment B analogous FU treatments were repeated for 5 days (rats 80+11 controls). Tumor volumes vs time, various blood parameters and survival times were recorded, and a log growth rate parameter log GR, a response index RI, and a toxicity index TI were calculated. The i.a. vs i.v. ratios for tumor concentrations of FU and total anabolites (F-Nucl) were >1 for nearly all treatments and increased with infusion time at the higher doses. F-Nucl in tumor correlated linearly with total fluorine concentration (Tot. F range 30-1100 nmol/g) over all treatments (r=0.92, slope=0.45, p<0.0001). For non-bolus i.v. treatments [FU+F-Nucl] decreased linearly with decreasing FU dose rate (r(2)=0.74, zero intercept), while i.a. treatments showed non-linear behavior. For non-bolus treatments the mean log GR per treatment group showed a negative correlation (r=-0.87) with log[F-Nucl]. The most effective non-toxic treatments were 25 mg/kg over 5 or 24 h; the i.a. route was superior to i.v. on the basis of [FU+F-Nucl], RI, the reduction in log GR, and Kaplan-Meier survival statistics. For liver and kidney Tot. F (>83% FU catabolites) reached ca. 3-4 and 6-7 micromol/g, respectively, at the highest dose rates for either route; F-Nucl were detected only for Tot. F>500 nmol/g and increased exponentially as Tot. F increased (toxic treatments). The concentrations of the main catabolite (alpha-fluoro-beta-alanine, FBAL) in tumor did not correlate with Tot. F but rather with FBAL levels in kidney (r=0.90, all treatments), indicating that uptake of liver-derived FBAL from the circulation is the major source of FBAL in tumor. 相似文献
33.
34.
A direct relationship between bronchodilator efficacy and toxicity by the measurement of serum theophylline concentrations is well established. This study evaluated, in children receiving either 12-hour (Theo-Dur) or an experimental 24-hour (Theo-Beads) preparation, the most common time to reach peak and trough levels in the serum. Twenty-three children with chronic asthma between the ages of 7 and 12 years participated in the study. Twelve received theophylline every 12 hours at a dose ranging from 400 to 800 mg per 24 hours. Eleven children received a 24-hour preparation at a dose ranging between 400 and 1000 mg per 24 hours. The results demonstrated no relationship between dosing interval and the appearance of peak or trough levels with Theo-Dur. Theo-Beads reached its peak in 9 to 11 children between six and eight hours and for 10 to 11 children the trough value was at the end of the dosing interval. 相似文献
35.
Sabine Siegemund Nicole Schütze Marina A. Freudenberg Manfred B. Lutz Reinhard K. Straubinger Gottfried Alber 《Immunobiology》2008,212(9-10):739-750
Induction of the interleukin-12 (IL-12) cytokine family comprising IL-12, IL-23, IL-27, and IL-12p40 by intracellular pathogens is required for orchestration of cell-mediated immune responses. Macrophages (MΦ) have been shown to be a source of IL-12 following TLR4-dependent activation by Salmonella (S.). In this study another antigen-presenting cell type, the conventional dendritic cell (cDC), was analyzed and its cytokine responses compared with those of MΦ. We generated bone marrow-derived conventional dendritic cells (BMDC) and macrophages (BMMΦ) by incubating murine bone marrow cells with supernatants containing granulocyte/macrophage colony-stimulating factor (GM-CSF) or macrophage colony-stimulating factor (M-CSF), respectively. Stimulation of BMDC and BMMΦ with S. enterica serovar Enteritidis (SE) or LPS resulted in the release of IL-12 and IL-23 by BMDC but not by BMMΦ. Furthermore, BMDC secreted approx. 20-fold more IL-12p40 and IL-27p28 than BMMΦ. However, BMDC and BMMΦ produced similar levels of IL-10. Using BMDC originating from wild-type (wt), TLR2def and TLR4def mice, we show that in BMDC the induction of IL-12, IL-23, and IL-27p28 by SE is dependent on TLR4, whereas low-level production of p40 is also mediated by pattern recognition receptors (PRR) other than TLR4. Interestingly, LPS- and SE-provoked responses of BMDC were remarkably similar indicating that LPS is the primary danger molecule of SE. Taken together, our results point to cDC rather than MΦ as the major producers of the IL-12 family members during in vitro infection with SE. The mechanisms of recognition of SE, however, appear to be the same for cDC and MΦ 相似文献
36.
G. Aumüller Paul-Martin Holterhus Lutz Konrad Burkhard von Rahden Olaf Hiort Murielle Esquenet Guido Verhoeven 《Anatomy and embryology》1998,197(3):199-208
As it is suggested that the androgen receptor mechanism is required for prostatic development, we attempted to determine
the appearance, expression and distribution of the androgen receptor in embryonic, infantile and pubertal human prostate.
Using mono- and polyclonal antibodies and a digoxigenin-labeled 713 bp riboprobe, the androgen receptor expression in paraffin
sections of fetal, infantile, and pubertal prostates was studied at the protein and RNA level. Under highly standardized conditions,
application of the polyclonal antibodies resulted in a weak cytoplasmic and nuclear labeling of the epithelium of fetal glands.
No immunoreaction was obtained with monoclonal antibodies. Applying the polyclonal antibody to pubertal and adult specimens,
immunoreactivity of the androgen receptor was positive in nuclei of adluminal and basal epithelial cells, in interstitial
and vascular smooth muscle cells and vascular endothelium, whereas ganglionic cells and enteroendocrine cells were negative.
In situ hybridization with the digoxigenin-labeled riboprobe gave clear positive results already in epithelium of very young
fetal specimens. A semiquantitative visual evaluation of in situ hybridizations showed that intermediate intensity of expression
was increased in pubertal and adult specimens, whereas strong expression was reduced in prostatic epithelium. Conclusions:
The essential findings are: (1) an early expression of androgen receptor mRNA in the fetal prostate; (2) no immunoreaction
of monoclonal antibodies against the androgen receptor in the same specimens, (3) a decrease of androgen receptor mRNA expression,
but increase in immunoreactivity of the androgen receptor protein with the onset of glandular maturation during puberty.
Accepted: 29 September 1997 相似文献
37.
A wide spectrum of protocols is available for rehabilitation after anterior cruciate ligament reconstruction, and little agreement exists on the specifics of strengthening exercises or the sequence of activities. In this article, we discuss the current rehabilitative techniques used at the Mayo Clinic for athletes who have undergone anterior cruciate ligament reconstruction. These techniques are based on established principles of rehabilitation, clinical experience, and new information about the related biomechanics of the knee. An illustrative case reflects the benefits of this rehabilitation program, which lasts up to 1 year and is divided into five stages. The early stages focus on protected mobilization and a strengthening program that emphasizes closed rather than open kinetic chain exercises. Later, neuromuscular-proprioceptive training and sport-specific agility training redevelop the reaction time and the "coordination engrams" necessary for athletic competition. High-quality surgical care and a closely supervised rehabilitation program, based on kinesiologic and biomechanical factors as they pertain to the anterior cruciate ligament, are necessary for a successful outcome. 相似文献
38.
39.
40.