全文获取类型
收费全文 | 1068篇 |
免费 | 61篇 |
国内免费 | 63篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 28篇 |
2021年 | 32篇 |
2020年 | 33篇 |
2019年 | 35篇 |
2018年 | 33篇 |
2017年 | 38篇 |
2016年 | 25篇 |
2015年 | 34篇 |
2014年 | 62篇 |
2013年 | 92篇 |
2012年 | 32篇 |
2011年 | 43篇 |
2010年 | 38篇 |
2009年 | 62篇 |
2008年 | 58篇 |
2007年 | 63篇 |
2006年 | 45篇 |
2005年 | 32篇 |
2004年 | 36篇 |
2003年 | 39篇 |
2002年 | 25篇 |
2001年 | 26篇 |
2000年 | 17篇 |
1999年 | 23篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 14篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有1192条查询结果,搜索用时 468 毫秒
111.
The use of proteomic approaches in investigating diseases is continuing to expand and has started to provide answers to substantial gaps in our understanding of disease pathogenesis as well as in the development of effective strategies for the early diagnosis and treatment of diseases. Biophysical techniques form a crucial part of the advanced proteomic techniques currently used and include mass spectrometry and protein separation techniques, such as two-dimensional gel electrophoresis and liquid chromatography. The application of biophysical proteomic techniques in the study of disease includes delineation of altered protein expression, not only at the whole-cell or tissue levels, but also in subcellular structures, protein complexes, and biological fluids. These techniques are also being used for the discovery of novel disease biomarkers, exploration of the pathogenesis of diseases, development of new diagnostic methodologies, and identification of new targets for therapeutics. Proteomic techniques also have the potential for accelerating drug development through more effective strategies for evaluating a specific drug’s therapeutic effects and toxicity. This article discusses the application of biophysical proteomic techniques in delineating cardiovascular disease and other diseases, as well as the limitations and future research directions required for these techniques to gain greater acceptance and have a larger impact. 相似文献
112.
以前期鉴定筛选的2个东乡野生稻强耐冷渐渗系(IL5243和IL5335)为试材,研究其减数分裂时期的染色体行为特征及外源基因的渗入分子证据。结果表明:(1)IL5243和IL5335中正常减数分裂的花粉母细胞分别达89.93%和90.22%,最终形成正常的成熟花粉粒,花粉离体萌发率分别为(83.03±2.82)%和(81.96±1.73)%,与受体亲本无显著性差异。(2)在减数分裂I中,2个耐冷渐渗系均观察到低频率异常染色体行为,如单价体、"8"字型二价体、多价体,以及后期I有少数花粉母细胞(3.95%~5.15%)存在落后染色体等,表明其染色体组之间发生了交换和重组;在粗线期,2个强耐冷渐渗系均观察到较高频率(IL5243和IL5335分别为27.0%和38.9%)的双核仁,而其双亲都是单核仁。(3)SSR标记和Structure分析进一步证实了栽培稻和野生稻染色体组间发生了交换重组,东乡野生稻部分DNA片段已渗入到强耐冷渐渗系中,这为水稻耐冷基因的挖掘与利用奠定了重要基础。 相似文献
113.
由于人类活动导致的海洋生境、生态系统以及生物资源的衰退已经引起了全球的高度重视。以生态修复的原理为基础,综述了海洋生境修复和生物资源养护的关键设施、关键技术、监测与效果评价以及综合管理的国内外研究进展,并对海洋生境修复与生物资源养护的研究热点和重点进行了展望,以期为我国海洋生境修复和生物资源养护提供参考。 相似文献
114.
程军关群熊小江陈林占方彪王斌 《现代生物医学进展》2012,12(24):4718-4720
目的:探讨应用微创技术治疗腰椎间盘突出症的疗效.方法:对我院脊柱骨科自2005年l1月~2010年10月收治的128例腰椎间盘突出症患者应用不同手术方式进行治疗,其中应用APLD( automated percutaneous lumbar discectomy)治疗单纯腰椎间盘突出症48例;应用MED(microendoscopic discectomy)治疗复杂型腰椎间盘突出症42例;应用传统后路椎板开窗技术治疗单纯腰椎间盘突出症38例;比较各组手术时间、术中出血、术后住院时间、疗效及并发症.术后均随访8个月~3年,观察复发情况.结果:三组不同手术方式手术时间及优良率比较差异无统计学意义(P>0.05),APLD及MED组术中出血量及术后住院时间与传统手术组比较,差异有显著性(P<0.05);术后随访疼痛全部缓解,无复发.结论:在严格掌握适应症的基础上,采用微创技术和采用传统手术治疗腰椎间盘突出症疗效相当,但微创技术创伤小、术中出血量少,术后住院日短,恢复快,优于传统手术. 相似文献
115.
Aims: To develop a simple, rapid and inexpensive soil DNA extraction protocol. Methods and Results: The protocol relies on the use of superparamagnetic silica‐magnetite nanoparticles for the isolation and purification of DNA from soil samples. DNA suitable for use in molecular biology applications was obtained from a number of soil samples. Conclusions: The DNA extracted using the tested method successfully permitted the PCR amplification of a fragment of the bacterial 16S rDNA gene. The extracted DNA could also be restriction endonuclease digested. Significance and Impact of the Study: The protocol reported here is simple and permits rapid isolation of PCR‐ready soil DNA. The method requires only small quantities of soil sample, is scalable and suitable for automation. 相似文献
116.
The diet of the Iberian hare (Lepus granatensis) was studied through microhistological pellet analysis in two areas from a mountain ecosystem in Central Portugal. Fecal
pellets were collected monthly in 24 plots spatially distributed throughout the two study areas. For each period, a sample
of 15 to 20 pellets was milled and 400 epidermal fragments were identified, by comparison with a reference collection. A wide
range of plant species was observed in hare’s diet. Grasses represent the basis of the Iberian hare diet, with frequencies
always higher than 50% in both study areas (annual average = 69.98%). Most of the 35 species of grasses assembled for the
reference collection (91.43%) were identified in the pellets. Nevertheless, only six of these were consumed in proportions
greater than 5%, being Anthoxanthum odoratum, Secale cereale and Agrostis spp. the species ingested in higher frequencies. The rate of grasses consumption reached 80.69% in winter but decreased in
summer to around 55%. In this season, a concurrent rise in the ingestion of other plant groups, like herbs and shrubs, and
of plant inflorescences was observed. This work provides the first results on the Iberian hare’s diet on mountain ecosystems,
and suggests that the Iberian hare diet in a mountain ecosystem is similar to the observed in L. europaeus and L. timidus. 相似文献
117.
118.
Günther S Hübschmann T Rudolf M Eschenhagen M Röske I Harms H Müller S 《Journal of microbiological methods》2008,75(1):127-134
Analysis of environmental bacteria on the single cell level often requires fixation to store the cells and to keep them in a state as near life-like as possible. Fixation procedures should furthermore counteract the increase of autofluorescence, cell clogging, and distortion of surface characteristics. Additionally, they should meet the specific fixation demands of both aerobically and anaerobically grown bacteria. A fixation method was developed based on metal solutions in combination with sodium azide. The fixation efficiencies of aluminium, barium, bismuth, cobalt, molybdenum, nickel, and tungsten salts were evaluated by flow cytometric measurement of the DNA contents as a bacterial population/community stability marker. Statistical equivalence testing was involved to permit highly reliable flow cytometric pattern evaluation. Investigations were carried out with pure cultures representing environmentally important metabolic and respiratory pathways as controls and with activated sludge as an example for highly diverse bacterial communities. A mixture of 5 mM barium chloride and nickel chloride, each and 10% sodium azide was found to be a suitable fixative for all tested bacteria. The described method provided good sample stability for at least 9 days. 相似文献
119.
A factorial experiment was carried out in order to assess the effects of four treatment steps in diatom processing techniques
(the quantity of hydrogen peroxide added to the sample, the time allowed to the digestion reaction, the use of centrifugation
and the method used to settle the frustules onto the coverslip) on different aspects of the quality of the resulting microscopic
slide: the concentration of organic and inorganic matter, the density, randomness and homogeneity of the frustule distribution
in the slide, and the abundance of broken frustules and girdle views. The results show no significant effects of any of the
experimental treatments on the proportion of broken frustules in the samples. No significant effects were related to the duration
of the oxidation reaction in any of the aspects evaluated in the quality of the slides. A sample:hydrogen peroxide ratio of
1:1 for a 6-h oxidizing reaction can be used to optimize the protocol. Despite being more time consuming, the use of successive
decantations instead of centrifuging is more appropriate to achieve better results. Slide quality can also be improved by
leaving the coverslips to dry at room temperature in order to improve the distribution of frustules. 相似文献
120.
V. Oikonomou M. Fotou F. Zagouri T. N. Sergentanis A. Nonni P. Athanassiadou T. Drouveli E. Patsouris E. Kotzia G. C. Zografos 《Cytopathology》2008,19(5):311-315
Objective: Imprint cytology provides a rapid preliminary diagnosis shortly after the completion of breast biopsy. This study aims to assess the validity of imprint cytology for the pre-operative diagnosis of non-palpable mammographic solid lesions excised by vacuum-assisted breast biopsy (VABB).
Methods: Seventy-two women with non-palpable Breast Imaging Reporting and Data System 3 and 4 mammographic solid lesions without microcalcifications underwent VABB on the stereotactic Fischer's table with 11-G Mammotome vacuum probes. Imprint samples were examined (Diff-Quick stain, modified Papanicolaou stain and May-Grünwald–Giemsa). The cores were dipped into a CytoRich Red Collection fluid for a few seconds in order to obtain samples with the use of the specimen wash. After the completion of cytological procedures, the core was prepared for routine pathological study. The pathologist was blind to the preliminary cytological results. The cytological and pathological diagnoses were comparatively evaluated.
Results: The sensitivity of the cytological imprints for cancer was 90%. The specificity of the method for cancer diagnosis was 100%. Two precursor lesions were present in the material: one case of atypical ductal hyperplasia, which was successfully detected, and one case of lobular neoplasia, which escaped detection. The cytological imprints were inadequate in four out of 72 cases (5.6%), but none of them were included within the malignant subgroup.
Conclusions: Imprint cytology seems to be an important adjunctive tool in the management of patients with non-palpable mammographic solid lesions. Its very satisfactory sensitivity and optimal specificity could establish its use in general clinical practice. 相似文献
Methods: Seventy-two women with non-palpable Breast Imaging Reporting and Data System 3 and 4 mammographic solid lesions without microcalcifications underwent VABB on the stereotactic Fischer's table with 11-G Mammotome vacuum probes. Imprint samples were examined (Diff-Quick stain, modified Papanicolaou stain and May-Grünwald–Giemsa). The cores were dipped into a CytoRich Red Collection fluid for a few seconds in order to obtain samples with the use of the specimen wash. After the completion of cytological procedures, the core was prepared for routine pathological study. The pathologist was blind to the preliminary cytological results. The cytological and pathological diagnoses were comparatively evaluated.
Results: The sensitivity of the cytological imprints for cancer was 90%. The specificity of the method for cancer diagnosis was 100%. Two precursor lesions were present in the material: one case of atypical ductal hyperplasia, which was successfully detected, and one case of lobular neoplasia, which escaped detection. The cytological imprints were inadequate in four out of 72 cases (5.6%), but none of them were included within the malignant subgroup.
Conclusions: Imprint cytology seems to be an important adjunctive tool in the management of patients with non-palpable mammographic solid lesions. Its very satisfactory sensitivity and optimal specificity could establish its use in general clinical practice. 相似文献