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921.
Fetal mesenchymal stem cells derived from human umbilical cord sustain primitive characteristics during extensive expansion 总被引:2,自引:0,他引:2
Jo CH Kim OS Park EY Kim BJ Lee JH Kang SB Lee JH Han HS Rhee SH Yoon KS 《Cell and tissue research》2008,334(3):423-433
Stem cells of fetal origin lie between embryonic and adult stem cells in terms of potentiality. Because of the ethical controversy
surrounding embryonic stem cells and the relatively inferior quality of adult stem cells, the use of fetal stem cells would
be an attractive option in future therapeutic applications. Here, we have investigated primitive characteristics of human
umbilical-cord-derived fetal mesenchymal stem cells (UC fMSCs) during extensive expansion. We have successfully isolated and
cultured UC fMSCs from all UC samples, but with two early fungal contaminations. UC fMSCs proliferated without significant
evidence of morphological changes, and the average cumulative population-doubling level was over 25 for about 3 months. UC
fMSCs showed the positive expression of several CD markers, known to be related to MSCs, including CD73 (SH-3, 4), CD90 (Thy-1),
CD105 (SH-2), CD117 (c-kit), and CD166 (ALCAM). They demonstrated primitive properties throughout the expansion period: multilineage
differentiation potentials examined by functional assays, a variety of pluripotent stem cell markers including Nanog, Oct-4,
Sox-2, Rex-1, SSEA-3, SSEA-4, Tra-1–60, and Tra-1–81, minimal evidence of senescence as shown by β-galactosidase staining,
and the consistent expression of telomerase activity. These results suggest that UC fMSCs have more primitive properties than
adult MSCs, which might make them a useful source of MSCs for clinical applications.
This work was supported by the Seoul R&BD Program (10548). 相似文献
922.
923.
L. A. Siena M. E. Sartor F. Espinoza C. L. Quarin J. P. A. Ortiz 《Sexual plant reproduction》2008,21(3):205-215
Gametophytic apomixis is an asexual mode of reproduction by seeds. This trait is present in several plant families and is
strongly associated with polyploidy. Paspalum rufum is a forage grass with sexual self-incompatible diploids (2n = 2x = 20) and aposporous-apomictic pseudogamous tetraploids (2n = 4x = 40). In previous work embryological observations of the diploid genotype Q3754 showed 8.8–26.8% of the ovaries having one
meiotic plus an aposporous-like embryo sac, suggesting some capability for apomictic reproduction. The objective of this work
was to characterize progenies derived from Q3754 to determine if aposporous sacs were functional and generated progenies via
apomixis at the diploid level. Re-examination of Q3754 ovaries showed that 12.5% of them contained one sexual plus an aposporous
sac confirming previous results. Progeny tests were carried out on two experimental families (H1 and S1) employing heterozygous RAPD marker loci. Family H1 was obtained crossing Q3754 with a natural diploid genotype (Q3861) and S1 derived from the induced self-pollination of Q3754. Genetic analysis of H1 showed that all individuals derived from sexual reproduction. However, 5 out of 95 plants from S1 showed the same heterozygous state as the mother plant for 14 RAPD loci suggesting a clonal origin. Further experiments,
designed to test the functionality of aposporous sacs by flow cytometric analyses, were carried out on a third family (M1) obtained by crossing Q3754 with the tetraploid plant Q3785. Histograms of 20 M1 plants showed 15 diploids (75%), 4 triploids (20%) and 1 tetraploid (5%). Triploids and the tetraploid may have originated
from functional aposporous embryo sacs. Likewise, the reconstruction of the developmental route of 40 individual seeds demonstrated
that 11 of them (27.5%) derived from fertilized aposporic sacs. The results presented in this work indicate that gametophytic
apomixis is effectively expressed at the diploid level in Paspalum rufum and could be the foundation of a recurrent auto-polyploidization process in the species. 相似文献
924.
Sumitaka Hasegawa Michiko Koshikawa Isao Takahashi Misao Hachiya Takako Furukawa Makoto Akashi Satoshi Yoshida Tsuneo Saga 《Journal of trace elements in medicine and biology》2008,22(3):248-255
BACKGROUND AND AIM: Molecular diagnostics and therapeutics of human mesothelioma using disease-related markers present major challenges in clinical practice. To identify biochemical alternations that would be markers of human mesothelioma, we measured the intracellular steady-state levels of biologically important trace metals such as manganese (Mn), copper (Cu), and zinc (Zn) in a human mesothelial cell line, MeT-5A, and in five human mesothelioma cell lines (MSTO-211H, NCI-H226, NCI-H2052, NCI-H2452, ACC-MESO-1) by inductively coupled plasma-mass spectrometry (ICP-MS). We also aimed to investigate whether the alterations were related to the intracellular status of metal-containing superoxide dismutase (SOD). RESULTS: There were no significant differences in the contents of the trace metals among MeT-5A, MSTO-211H, and ACC-MESO-1 cells. However, each of the other three mesothelioma cell lines had a unique characteristic in terms of the intracellular amounts of the metals; NCI-H226 contained an extremely high level of Mn, an amount 7.3-fold higher than that in MeT-5A. NCI-H2052 had significantly higher amounts of Cu (3.4-fold) and Zn (1.3-fold) compared with MeT-5A. NCI-H2452 contained about 5.8-fold the amount of Cu and 2.5-fold that of Mn compared with MeT-5A. As for the intracellular levels of copper/zinc-SOD (Cu/Zn-SOD) and manganese-SOD (Mn-SOD), those of Cu/Zn-SOD were relatively unchanged among the cells tested, and no notable correlation with Cu or Zn contents was observed. On the other hand, all mesothelioma cells highly expressed Mn-SOD compared with MeT-5A, and a very high expression of the enzyme with a robust activity was observed in the two mesothelioma cells (NCI-H226, NCI-H2452) containing a large amount of Mn. CONCLUSIONS: In comparison with MeT-5A human mesothelial cells, some human mesothelioma cells had significantly higher amounts of Mn or Cu and one mesothelioma cell had a significantly higher amount of Zn. Interestingly, all mesothelioma cells overexpressed Mn-SOD compared with MeT-5A, and the cells whose Mn-SOD activity was increased contained higher amounts of Mn. It seemed that intracellular Mn content was positively correlated with Mn-SOD, suggesting that the intracellular Mn level is associated with Mn-SOD activity. These biochemical signatures could be potential disease-related markers of mesothelioma. 相似文献
925.
Annalisa Bargellini Isabella Marchesi Laura Rizzi Laura Cauteruccio Roberto Masironi Marco Simioli Paola Borella 《Journal of trace elements in medicine and biology》2008,22(3):234-241
The main objective of this work was to evaluate the interaction between selenium concentration in both commercial and Se-enriched eggs and other essential/toxic elements (Ca, Mg, Fe, Zn, Pb, and Cd), taking into account a possible synergic action of iodine. Commercial eggs were purchased from several sale points or directly from the producers (farmyard eggs). Fortified eggs were obtained by supplementing chickenfeed for 6 weeks with Se as sodium selenite (1.0mug/g Se) or Se plus iodine (1.0mug/g Se+3.7mug/g I). Se in experimental egg yolks significantly increased over the basic value by 39% in the Se group and 61% in the Se+I group, suggesting that I addition may enhance Se absorption. Levels of Se in commercial yolks were identical in free-range, barn or battery eggs, but significantly lower in farmyard and higher in organic eggs where the Se content approximated that found in Se fortified eggs. A significant reduction in Cd was observed in Se+I treated yolks compared to both control and Se alone diet, thus suggesting a high sensitivity of Cd to the detoxifying effect of Se combined with I. Furthermore, Se+I supplementation was associated with a significant Zn reduction, a finding which needs clarification to avoid attempts to maximize one component affecting the levels of other essential elements. 相似文献
926.
We investigate the nonlinear properties of dentine from the upper canines of coyotes Canis latrans with bending tests. With the results we predict the behavior of whole canines under load. Coyote dentine is not homogeneous but is stronger and more ductile farther away from the pulp cavity. The modulus of rupture (MOR) first increases and then declines with distance from the pulp cavity. Our analysis of the composite nature of dentine produced by these gradients indicates that there may be an adaptive explanation with the composite having nearly the strength of the strongest dentine and a work of fracture greater than even the most ductile dentine. Coyote dentine is considerably stronger than human dentine. In coyotes, the peak MOR, a measure of bending strength, is 480 MPa, compared with a maximum of 225 MPa for human dentine. This value is about the same as the weakest coyote dentine that we found near the pulp cavity. Finally, enamel plays, at most, a small role in the bending strength of the whole tooth. Our results indicate that enamel under tension adds little to strength, but we cannot dismiss a small role for enamel in compression. 相似文献
927.
Colletotrichum lindemuthianum, the causal agent of anthracnose in the common bean (Phaseolus vulgaris), presents a wide genetic and pathogenic variability that gives rise to complications in the development of resistant bean
cultivars. The aim of this study was to identify the variability within race 65 of C. lindemuthianum, the race most commonly encountered in Brazil, through randomly amplified polymorphic DNA (RAPD) and anastomosis analyses.
Thirteen isolates of race 65, collected in different years and from various host cultivars located in diverse areas of the
state of Minas Gerais, Brazil, were investigated. Twenty-four RAPD primers were employed and 83 polymorphic bands amplified.
Genetic similarities were estimated from the Sorensen-Dice coefficient and ranged from 0.54 to 0.82. The dendrogram obtained
by cluster analysis classified the isolates into 11 separate groups. For the purposes of the analysis of anastomosis, isolates
were considered to be compatible when the fusion of hyphae from different isolates could be observed. The proportion of compatible
reactions for each isolate was estimated and similarity estimates, based on the Russel & Rao coefficient, ranged from 0.28
to 0.85. Isolates were classified into 11 anastomosis groups, 10 of which were formed by only one isolate. Although isolates
LV61, LV73 and LV58 were classified in the same anastomosis group, they were genetically distinct according to RAPD analysis.
Results from both RAPD and anastomosis analyses revealed great variability within C. lindemuthianum race 65. 相似文献
928.
929.
Ac/Ds(GUS)结构介导的水稻启动子捕获系统的建立 总被引:5,自引:0,他引:5
构建了基于Activator/Dissociation(β-glucuronidase)[简称Ac/Ds(GUS)]结构的捕获质粒p13B,用于分离水稻基因启动子.以此质粒用衣杆菌介导的方法转化粳稻品种中花11的胚性愈伤组织,对获得的18个独立转化株的T2代植株进行了抗除草剂筛选,从141个抗除草剂转基因植株中用PCR方法检测到其中37株是Ds因子发生了转座的植株,而且这种转座到新位置上的Ds因子是遗传的.初步观察到其中5株的GUS染色呈阳性. 相似文献
930.
吡咯赖氨酸在产甲烷菌的甲胺甲基转移酶中发现,是目前已知的第 22 种参与蛋白质生物合成的氨基酸,与标准氨基酸不同的是,它由终止密码子 UAG 的有义编码形成 . 与之对应的在产甲烷菌中也含有特异的吡咯赖氨酰 -tRNA 合成酶 (PylRS) 和吡咯赖氨酸 tRNA (tRNAPyl). tRNAPyl具有不同于经典 tRNA 的特殊结构 . 产甲烷菌通过直接途径和间接途径这两种途径生成吡咯赖氨酰 -tRNAPyl(Pyl-tRNAPyl) ,它还可能通过 mRNA 上的特殊结构以及其他还未发现的机制,控制 UAG 编码成为终止密码子或者吡咯赖氨酸 . 比较了吡咯赖氨酸与另一种非标准氨基酸,第 21 种氨基酸———硒代半胱氨酸的相似点与不同点 . 相似文献