全文获取类型
收费全文 | 8553篇 |
免费 | 918篇 |
国内免费 | 1271篇 |
出版年
2024年 | 15篇 |
2023年 | 206篇 |
2022年 | 239篇 |
2021年 | 336篇 |
2020年 | 393篇 |
2019年 | 448篇 |
2018年 | 425篇 |
2017年 | 457篇 |
2016年 | 477篇 |
2015年 | 437篇 |
2014年 | 444篇 |
2013年 | 602篇 |
2012年 | 374篇 |
2011年 | 412篇 |
2010年 | 336篇 |
2009年 | 414篇 |
2008年 | 410篇 |
2007年 | 454篇 |
2006年 | 408篇 |
2005年 | 388篇 |
2004年 | 284篇 |
2003年 | 308篇 |
2002年 | 245篇 |
2001年 | 214篇 |
2000年 | 230篇 |
1999年 | 180篇 |
1998年 | 159篇 |
1997年 | 129篇 |
1996年 | 106篇 |
1995年 | 134篇 |
1994年 | 124篇 |
1993年 | 144篇 |
1992年 | 115篇 |
1991年 | 96篇 |
1990年 | 87篇 |
1989年 | 72篇 |
1988年 | 62篇 |
1987年 | 66篇 |
1986年 | 35篇 |
1985年 | 54篇 |
1984年 | 37篇 |
1983年 | 21篇 |
1982年 | 46篇 |
1981年 | 33篇 |
1980年 | 24篇 |
1979年 | 15篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
131.
The soybean embryo factor binding sequence in the glycinin A2B1a gene promoter was delimited to an A/T-rich 9 bp sequence, 5-TAATAATTT-3, designated as the glycinin box, by DNA footprinting and gel mobility shift assay using synthetic oligonucleotides. It was shown that the interaction with the factor takes place at a defined DNA sequence rather than at random A/T-rich sequence blocks in the glycinin 5 flanking region. There are four glycinin boxes in the quantitative regulatory region between positions – 545 and – 378 of the glycinin A2B1a promoter. Multiple nonamer motifs similar to the glycinin box were also found in the equivalent regions of other glycinin and legumin promoters, suggesting that they must be conserved as a binding site for the embryo factor that activates the differential and stage-specific expression of seed 11S globulin genes in leguminous plants. 相似文献
132.
Storage at 6.5°C under moderate vacuum effectively prevented growth of Aeromonas hydrophila on chicory endive, but had only a limited inhibitory effect on the growth of the organism on mung bean sprouts. Growth of Listeria monocytogenes on chicory endive was strongly stimulated under these conditions, whereas it was decreased on mung-bean sprouts. 相似文献
133.
Two methods of storing fine needle aspirates were compared in 14 patients with breast cancer. the methods of storage were: (1) as a Cytospin slide prepared immediately from the aspirated material and stored at −80°C; (2) as a suspension of cells in tissue culture medium, stored at −80°C. the effect of storage on the cells was assessed by means of an oestrogen receptor immunocytochemical assay (ER-ICA). an ER positivity of 100% was obtained by ER-ICA staining of cells after storage method 1, whilst all of the specimens stored by method 2 were ER-negative. the data demonstrate that cells stored in tissue culture medium at −80°C are not suitable for ER measurement. the storage method of choice for specimens intended for ERICA is as a Cytospin slide. the ER status of cells deposited on Cytospin slides prepared immediately and stored at −80°C for 2 years could be demonstrated despite the delay in processing the specimen. 相似文献
134.
Martin Fotso Jean-Louis Azanza Remy Pasquet Jacques Raymond 《Plant Systematics and Evolution》1994,191(1-2):39-56
81 wild forms and 110 cultivated cowpea,Vigna unguiculata, accessions from 21 countries of Africa were screened for variability in seed storage proteins. Total seed proteins, albumin and globulin fractions were investigated by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF) of nonreduced and/or reduced samples in one- and two-dimensional procedures. The globulin fraction is heterogeneous in molecular weight and contains both legumin-like components and three to six nondisulfide-linked subunits. Three globulin subunits, with molecular weights 110, 76, and 41 kD were found to be composed of disulfide-linked polypeptides. In the nondisulfide-linked fraction, both cultivated and wild forms exhibited patterns of four types (A–D). This fraction contains polypeptide subunits of molecular weights 62, 56, and 52 kD for A type, 62, 56, 54, and 52 kD for B type, 62, 56, 52, and 50 kD for C type, and at least 62, 56, 54, 52, 50, and 49 kD for D type. These subunits present similar multiple charge forms but C and D types possess more basic specific 50 and 49 kD nondisulfide linked components. Major albumin fraction contains subunits of 94, 86, 32, and 24kD. No infraspecific variation was observed in albumin or legumin-like fractions. The discussion is focussed on the relations between genetic variability assessed by storage protein coding genes and phenotypic variability. 相似文献
135.
薏苡胚发育及贮藏营养物质积累的研究 总被引:4,自引:0,他引:4
薏苡(Coix lacrym a-jobi)胚发育分下列各期:棒形胚前的原胚期、棒形胚期、胚芽鞘期、1叶期、2 叶期、3叶期、4 叶期、5 叶期及6叶期成熟胚。3 叶期胚具1 条不定根(种子根),4 叶期具2 条,5 叶期及成熟胚期具3 条。不定根与胚根排成1 纵行。营养物质最先在盾片细胞中积累。开花后9 天的1 叶期胚,在盾片、胚芽鞘及胚轴细胞中积累了淀粉,以后遍及成熟胚的各部分。淀粉粒含量与器官发生及生长顺序成正相关,但发育后期,盾片细胞内的淀粉粒含量下降。开花后10 天,盾片细胞中形成含晶体的蛋白质体,晶体含蛋白质及植酸钙镁。以后,这种蛋白质体增多、增大。同时,又形成不含晶体的蛋白质体。一定时期,含晶体的蛋白质体消失,不含晶体的蛋白质体增多,直到胚成熟。开花后13 天,胚芽鞘上部细胞形成蛋白质体。以后遍及成熟胚的各部分,器官发生越早,所含蛋白质体越多、越大。开花后10 天,盾片细胞中产生了脂体,成熟胚的盾片细胞,含有大量的脂体。还观察了胚发育各期与颖果及盾片长度的对应关系 相似文献
136.
Gary C. du Moulin Zorina Pitkin Yuan-Jin Shen Evelyn Conti Jean Ko Stewart Carla Charles Dylan Hamilton 《Cytotechnology》1994,15(1-3):365-372
Somatic cell and gene therapy involve the application of biological technologies to an individual patient through the use of living cells which provide a therapeutic benefit (Aliski, 1991). Various forms of cellular and gene therapies are being developed and evaluated in an increasing number of clinical trials for congential and acquired disorders. The potential and progress of these therapeutic applications have resulted in an increasing effort by the Food and Drug Administration (FDA) to develop the regulatory framework under which these therapeutic approaches would insure safety and efficacy, the primary mandate of the FDA.Over five years ago Cellcor began to define the parameters, specifications, and conditions relevant to a Quality Assurance/Quality Control (QA/QC) program that has evolved to insure safety and maximize the efficacy of applications of the company'sex vivo technology, autolymphocyte therapy. Autolymphocyte therapy is an outpatient form of somatic cell immunotherapy based upon the infusion of T cells that have been activatedex vivo using a combination of previously generated autologous cytokines and an anti-CD3 monoclonal antibody.We have been able to demonstrate the feasibility for the safe, controlled, and consistent preparation and delivery of a cellular therapy by application of relevant GMP regulations. This presentation reviews aspects of this program and chronicles our experience which at present amounts to over 4400 infusions for over 700 patients. This program provides a high degree of assurance that a cellular therapy program can be carried out in a multisite mode involving hundreds of patients through the strict adherence to cGMP as set forth in existing regulations. It would be prudent that developers of cellular andex vivo gene therapies establish a similar cell processing and QA/QC infrastructure at an early developmental stage to optimize safety and reproducibility and facilitate regulatory review. 相似文献
137.
138.
139.
140.
长白山站的研究数据库管理系统翟永华,赵士洞(中国科学院沈阳应用生态研究所110015)Date-BaseManagementSysteminChangbaishanForestEcosystemResearchStation.¥ZhaiYonghua... 相似文献