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951.
Constitutively active type I insulin-like growth factor receptor causes transformation and xenograft growth of immortalized mammary epithelial cells and is accompanied by an epithelial-to-mesenchymal transition mediated by NF-kappaB and snail
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Induction of oocyte-like cells from mouse embryonic stem cells by co-culture with ovarian granulosa cells 总被引:2,自引:0,他引:2
Qing T Shi Y Qin H Ye X Wei W Liu H Ding M Deng H 《Differentiation; research in biological diversity》2007,75(10):902-911
Abstract In vitro derivation of oocytes from embryonic stem (ES) cells has the potential to be an important tool for studying oogenesis as well as advancing the field of therapeutic cloning by providing an alternative source of oocytes. Here, we demonstrate a novel, two-step method for inducing mouse ES cells to differentiate into oocyte-like cells using mouse ovarian granulosa cells. First, primordial germ cells (PGCs) were differentiated within the embryonic body (EB) cells around day 4 as defined by the expression of PGC-specific markers and were distinguished from undifferentiated ES cells. Second, day 4 EB cells were co-cultured with ovarian granulosa cells. After 10 days, these cells formed germ cell colonies as indicated by the expression of the two germ cell markers Mvh and SCP3. These cells also expressed the oocyte-specific genes Fig α, GDF-9 , and ZP1-3 but not any testis-specific genes by RT-PCR analysis. EB cultured alone or cultured in granulosa cell-conditioned medium did not express any of these oocyte-specific markers. In addition, EB co-cultured with Chinese hamster ovary (CHO) cells or cultured in CHO cell-conditioned medium did not express all of these oocyte-specific markers. Immunocytochemistry analysis using Mvh and GDF-9 antibodies confirmed that some Mvh and GDF-9 double-positive oocyte-like cells were generated within the germ cell colonies. Our results demonstrate that granulosa cells were effective in inducing the differentiation of ES cell-derived PGCs into oocyte-like cells through direct cell-to-cell contacts. Our method offers a novel in vitro system for studying oogenesis; in particular, for studying the interactions between PGCs and granulosa cells. 相似文献
955.
Liu Z Dong Z Yang Z Chen Q Pan Y Yang Y Cui P Zhang X Zhang JT 《Differentiation; research in biological diversity》2007,75(7):652-661
Eukaryotic initiation factor 3a (eIF3a) has been suggested to play a regulatory role in mRNA translation. Decreased eIF3a expression has been observed in differentiated cells while higher levels have been observed in cancer cells. However, whether eIF3a plays any role in differentiation and development is currently unknown. Here, we investigated eIF3a expression during mouse development and its role in differentiation of colon epithelial cells. We found that eIF3a expression was higher in fetal tissues compared with postnatal ones. Its expression in intestine, stomach, and lung abruptly stopped on the 18th day in gestation but persisted in liver, kidney, and heart throughout the postnatal stage at decreased levels. Similarly, eIF3a expression in colon cancer cell lines, HT-29 and Caco-2, drastically decreased prior to differentiation. Enforced eIF3a expression inhibited while knocking it down using small interference RNA promoted Caco-2 differentiation. Thus, eIF3a may play some roles in development and differentiation and that the decreased eIF3a expression may be a pre-requisite of intestinal epithelial cell differentiation. 相似文献
956.
Tissue-engineered replacement of diseased or damaged tissue has become a reality for some types of tissue, such as skin and
cartilage. Tissue-engineered corneal stroma represents a promising concept to overcome the limitations of cornea replacement
with allograft. In this study, porcine cornea was decellularized by a series of extraction methods, and the in vivo biocompatibility
of the scaffold was measured subcutaneously in rabbits (n = 8). These were not acutely rejected and no abscesses were observed by hematoxylin and eosin staining at the 8th week, indicating
that the scaffolds had good biocompatibility. To investigate the potential value of clinical applications, rabbit stromal
keratocytes were implanted onto decellularized scaffolds to fabricate tissue-engineered corneal stroma. Allograft, tissue-engineered
corneal stroma, or scaffolds were implanted into a model of corneal ulcer. The survival and reconstruction of corneal transplantation
were morphologically evaluated by light and electron microscopy until the 32nd week after implantation. Experiments involving
transplantation indicated that the epithelial and stromal defect healed quickly, with improvement in corneal clarity. The
integration of the graft was accompanied by neurite ingrowth from the host tissue. By 16 weeks after transplantation, the
cornea had gradually regained an intact state similar to that of normal cornea. Our results demonstrate that the tissue-engineered
corneal stroma with allogenetic cells is a promising therapeutic method for corneal injury.
This study was supported by the Nature Science Foundation of China (project no. 30572046) and the Development of High and
New Science and Technology (863 Project) of China (2002AA205041, 2005AA205241). 相似文献
957.
Gao X 《Biometrical journal. Biometrische Zeitschrift》2007,49(5):774-788
We develop a nonparametric imputation technique to test for the treatment effects in a nonparametric two-factor mixed model with incomplete data. Within each block, an arbitrary covariance structure of the repeated measurements is assumed without the explicit parametrization of the joint multivariate distribution. The number of repeated measurements is uniformly bounded whereas the number of blocks tends to infinity. The essential idea of the nonparametric imputation is to replace the unknown indicator functions of pairwise comparisons by the corresponding empirical distribution functions. The proposed nonparametric imputation method holds valid under the missing completely at random (MCAR) mechanism. We apply the nonparametric imputation on Brunner and Dette's method for the nonparametric two-factor mixed model and this extension results in a weighted partial rank transform statistic. Asymptotic relative efficiency of the nonparametric imputation method with the complete data versus the incomplete data is derived to quantify the efficiency loss due to the missing data. Monte Carlo simulation studies are conducted to demonstrate the validity and power of the proposed method in comparison with other existing methods. A migraine severity score data set is analyzed to demonstrate the application of the proposed method in the analysis of missing data. 相似文献
958.
In this paper, we investigated the action of huwentoxin-I (HWTX-I) purified from the venom of the Chinese bird spider Ornithoctonus huwena on Ca(2+), Na(+) channels of adult rat dorsal root ganglion (DRG) neurons. The results showed that huwentoxin-I could reduce the peak currents of N-type Ca(2+) channels (IC(50) approximately 100 nM) and TTX-S Na(+) channels (IC(50) approximately 55 nM), whereas no effect was detected on TTX-R Na(+) channels. The comparative studies indicated that the selectivity of HWTX-I on Ca(2+) channels was higher that of MVIIA and approximately the same as that of GVIA. HWTX-I is the first discovered toxin with the cross channel activities from the spider O. huwena venom similar to micro O-conotoxins MrVIA and MrVIB. 相似文献
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