全文获取类型
收费全文 | 906篇 |
免费 | 51篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 26篇 |
妇产科学 | 9篇 |
基础医学 | 168篇 |
口腔科学 | 30篇 |
临床医学 | 119篇 |
内科学 | 164篇 |
皮肤病学 | 4篇 |
神经病学 | 19篇 |
特种医学 | 22篇 |
外科学 | 71篇 |
综合类 | 161篇 |
预防医学 | 42篇 |
眼科学 | 8篇 |
药学 | 91篇 |
中国医学 | 13篇 |
肿瘤学 | 22篇 |
出版年
2023年 | 8篇 |
2022年 | 48篇 |
2021年 | 55篇 |
2020年 | 26篇 |
2019年 | 20篇 |
2018年 | 17篇 |
2017年 | 20篇 |
2016年 | 20篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 40篇 |
2012年 | 29篇 |
2011年 | 41篇 |
2010年 | 42篇 |
2009年 | 30篇 |
2008年 | 32篇 |
2007年 | 30篇 |
2006年 | 37篇 |
2005年 | 32篇 |
2004年 | 27篇 |
2003年 | 22篇 |
2002年 | 22篇 |
2001年 | 16篇 |
2000年 | 21篇 |
1999年 | 25篇 |
1998年 | 19篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 30篇 |
1994年 | 19篇 |
1993年 | 12篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 16篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 7篇 |
1972年 | 1篇 |
排序方式: 共有972条查询结果,搜索用时 15 毫秒
1.
2.
本文通过酯交换反应合成了一系列脂肪族聚丁二酸酯,对他们的结构和性能作了表征。发现聚酯存在多晶现象,其熔点有奇偶性变化规律。探索了由此系列聚酯与高氯酸锂形成的固体电解质的结构和离子导电性。无机盐的加入提高了电解质的玻璃化温度但降低了聚酯的熔点及结晶度。聚酯电解质的晶体类似于聚酯,其无机盐主要溶解于聚酯的无定形区域。聚酯系列电解质的导电率也有偶奇效应,与熔点变化相反;熔点高的电解质导电率低,熔点低的电解质导电率高。电解质的导电率随温度改变而变化,在室温下电解质的导电率可达10~(-6)s/cm。高分子链上侧基的引入将大大降低电解质的导电性。 相似文献
3.
TUVP手术时间对血红蛋白及电解质的影响 总被引:2,自引:0,他引:2
目的 了解经尿道前列腺汽化电切手术时间对血红蛋白及血清电解质的影响。方法 对64例经尿道前列腺汽化电切术患按手术时间分组,观察手术前后血红蛋白及血清电解质的变化。结果 手术时间对血清电解质的降低有的影响,对血红蛋白降低的影响不显。结论 减少TUR综合征的关键是要操作熟练,缩短手术时间及手术中注意止血。 相似文献
4.
Peter Gode Göran Lindbergh Göran Sundholm 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》2002,518(2):115-122
A new method to study permeation of gases in proton conducting membranes using a cylindrical microelectrode is presented. The focus of this work was to develop an in-situ method to study transport properties of hydrogen and oxygen close to real fuel cell operating conditions. The gas permeability is strongly affected by the change of water content in the membrane and it is therefore of advantage that, by using this method, measurements can be carried out over a wide range of relative humidities. The numerical method makes it possible to separate the diffusion coefficient and the concentration of dissolved gas in the membrane and also allows kinetic limitations to be taken into account. Chronoamperometric measurements on Nafion® 117 were successfully evaluated numerically. Experiments at temperatures of 25 and 60 °C with respect to oxygen permeation and at 60 °C for hydrogen permeation at relative humidities in the range 30–94% are presented. The reproducibility of data was excellent when measuring with different microelectrodes on the same membrane sample, but differed when measuring on different samples. In general, the permeability increases with increasing temperature and relative humidity. 相似文献
5.
6.
Mayumi Matsuta Yuko Imamura Morimasa Matsuta Saiichi Kon Kohsuke Sasaki 《The Journal of dermatology》1994,21(1):14-19
We have applied DNA flow cytometric analysis to paraffin-embedded tissue sections of primary malignant melanomas. Conventionally, flow cytometric analysis of paraffin-embedded tissue sections has been done by the method of Hedley et al. We added ultrasound treatment to the method of Hedley et al. and a lower value of coefficient of variation was shown. Furthermore, a new technique, fluorescence in situ hybridization with a chromosome-specific repetitive DNA probe, was used for the analysis of chromosomal numerical aberrations in the same paraffin-embedded tissue sections. The DNA flow cytometric analysis showed that in 8 cases six primary malignant melanomas were of the aneuploid pattern and two cases of lentigo maligna (melamona in situ) were of the diploid pattern. By fluorescence in situ hybridization, the two cases with the diploid pattern had spots/nucleus of 1.28 and 1.12, and those with the aneuploid pattern had spots/nucleus from 2.01 to 2.27. Only one nodular melanoma in an aneuploid case showed spots/nucleus of 1.71. These data indicate that fluorescence in situ hybridization with chromosome-specific repetitive DNA probes can serve as a cytogenetic tool for the analysis of interphase nuclei of solid human tumors and may be useful for the study of tumor cell heterogeneity. 相似文献
7.
人体肥大细胞的多态性已受到广泛关注,对于肥大细胞分型的研究已成为这一问题的关键。本实验研究了42例人大肠4种肥大细胞类群光镜特征,其中两种为作者的新近发现,暂命名为结缔组织肥大细胞-1(CTMC-1)和粘膜肥大细胞-1(MMC-1)。 相似文献
8.
A luminescence-microscopic study using acridine orange with a short-term culture of human cells showed that DNA melting profiles of the chromatin of intact lymphocytes of healthy donors are curves with maxima (F 530) in the temperature regions of 45, 65, 78, 85, 88, and 92°C (P<0.01). The melting profiles of lymphocytes of patients with Down's syndrome are curves with maxima in the temperature regions of 65, 85, 88, and 92°C (P<0.01). The absence of a decrease in the intensity of fluorescence between 78 and 85°C is evidently due to the greater degree of condensation of certain regions of the chromatin complex of the trisomic cells. The possible mechanisms of the structural changes in the interphase chromatin, of human lymphocytes under the influence of temperature are discussed.Institute of Medical Genetics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 6, pp. 672–674, June, 1976. 相似文献
9.
Roger Rick Adolf Dörge Uri Katz Richard Bauer Klaus Thurau 《Pflügers Archiv : European journal of physiology》1980,385(1):1-10
The effect of saline adaptation on the intracellular Na, K, Cl, P concentrations and dry weight content of the toad skin epithelium (Bufo viridis) was studied using the technique of electron microprobe analysis. The measurements were performed on isolated abdominal skins either directly after dissection or after additional incubation in Ussing-type chambers.Adaptations of the toads to increasing NaCl concentrations for 7 days resulted in increased blood plasma osmolarity and a parallel increase in the cellular electrolyte, P and dry weight concentrations of the epithelium, the K increase representing the most significant fraction of the intracellular osmolarity increase. No evidence was obtained to show that the nucleus and cytoplasm reacted differently from each other and all living epithelial cell types basically showed the same response.Incubation of the isolated skins under control conditions showed a drastic inhibition of the transepithelial Na transport after adaptation to high salinities. In spite of the large variations in the transport rate almost identical intracellular electrolyte concentrations were observed. In tap water adapted toads the average cellular concentrations were 8.8 mmole/kg wet weight for Na, 109.6 for K, 41.5 for Cl, and 135.3 for P, respectively. Incubation of the skin with Ringer's solution of different osmolarities demonstrated that the epithelial cells are in osmotic equilibrium with the inner bathing solution. The results are consistent with the view that the osmotic adaptation is mainly accomplished by the movement of water.This work was supported by grants from the Deutsche Forschungsgemeinschaft and the Stiftung Volkswagenwerk 相似文献
10.
Towards unlimited colors for fluorescence in-situ
hybridization (FISH) 总被引:13,自引:0,他引:13
We describe a FISH protocol that allows rehybridization of complex DNA probes up to four times to the same specimen. This strategy, which we termed ReFISH, opens a wide range of new applications to conventional band pass filter epifluorescence microscopy. These include M-FISH karyotyping and cross-species color banding that emulate multiplex probe sets labeled with up to 12 fluorochromes in sequential hybridizations to the same specimen. We designed a human 24-color karyotyping probe set in combination with a 29-color cross-species color banding probe set using gibbon painting probes. Applying the ReFISH principle, 53 painting probes on individual metaphases were discriminated. This allowed simultaneous screening for inter- and intrachromosomal rearrangements on normal human diploid cells, a HeLa derived cell line, and highly rearranged gibbon chromosomes. Furthermore, the present ReFISH experiments successfully combine 24-color FISH with laser scanning confocal microscopy to study the 3D organization of all 46 human chromosome territories in individual interphase cell nuclei. 相似文献